A sportsbook never has to lie about a card or a wheel. It just prices the math — and the price is hidden inside numbers that look like rewards. Every bet below is a real market. Flip Casino Mode to watch the friendly app reframe each one as a gift, exactly the way the real ones do. Every figure here is documented and reproducible.
CASINO MODE: OFF (the math, plainly)
Odds shown as true cost. No "boosts," no "free," no spin.
SCAM 1 The Vig
Two teams. A genuine 50/50 coin-flip. Pick a side and "win" — then check whether you were ever paid like it was even money.
Spread market · both sides priced −110
Hawks
−110
implied 52.38%
Wolves
−110
implied 52.38%
stake $100
A true 50/50. If this were fair, $100 wins $100. Watch what it actually pays.
Fair payout (even money)
$100
Book's payout (−110)
$90.91
Two implied probs sum to
104.76%
House hold on this market
4.55%
The math: 52.38% × 2 = 104.76%, and the extra 4.76 points is the rent
American odds of −110 mean "risk $110 to win $100." Implied probability = 110 ÷ (110+100) = 110/210 = 52.38%. The book prices both sides at 52.38%, so the two probabilities sum to 104.76% — that surplus is the overround. The house hold = (overround − 1) ÷ overround = 4.76/104.76 = 4.55%. A genuine coin flip should pay decimal 2.00 (+100); −110 is decimal 1.909, so you're handed +90.91 on a bet that should pay +100. There is no such thing as an even-money bet at a sportsbook.
Source: Steven D. Levitt, "Why are gambling markets organised so differently from financial markets?" The Economic Journal 114(495):223–246 (2004) — documents the bookmaker spread and that realized hold exceeds the nominal vig because books also exploit lopsided bettor preferences.
SCAM 2 Parlay Hold Inflation
The app's favorite product. Each leg is a fair coin-flip priced at −110. Stack them and the small per-leg tax compounds — the more legs you add, the more of your fair payout silently vanishes. Add legs and watch.
Your parlay slip · 3 legs · $100 stake
stake $100
True fair payout
$700
decimal 8.00 · +700
Book's offer (−110 legs)
$595
decimal 6.96 · +595
House value retained by this parlay 13.0%
13.0% hold
Three true coin-flips should pay +700. Stacking three −110 legs, the book pays +595 — and markets it up to "+600."
You're shorted on this slip
$105
Per-leg formula
1−0.9546ⁿ
Why parlays are the casino of the sportsbook — hold per leg count
Legs
Fair odds
Offered
House hold
1
+100
−110
4.5%
2
+300
+265
8.9%
3
+700
+595
13.0%
4
+1500
+1228
17.0%
5
+3100
+2436
20.8%
A real book builds a parlay by multiplying the actual −110 leg odds (decimal 1.9091 each). As a fraction of a fair coin-flip (2.00), each leg pays 1.9091/2 = 0.9546, so an N-leg parlay returns 0.9546ⁿ of fair value and the hold is 1 − 0.9546ⁿ. A 3-leg coin-flip parlay's true price is decimal 8.00 (+700); the book stacks to 1.9091³ = 6.96 (+595) and rounds the marketing line up to "+600."
Source: New Jersey Division of Gaming Enforcement, monthly press releases (Sept 2024 data): parlays were 72.5% of online sports-betting revenue at a 24.2% hold, versus a 4.4% hold on straight bets — books earn the overwhelming majority of their margin from the product with the highest compounded hold.
SCAM 3 The "Free Bet" (stake not returned)
A "$100 free bet" is not $100. With a free bet you keep the winnings but never the stake — so its real worth is Face × (1 − 1/decimal). And the instinct to play it safe near even money is the worst thing you can do with it.
$100
+100
A "$100 free bet" placed at +100 (decimal 2.00) is really worth$50.00
At even money you only collect the winnings, not the stake — so you "get back" exactly half the face value. To extract more, you must take on more risk, the opposite of the safe instinct.
Industry "good" conversion
~70%
So your "$100 free bet" ≈
~$70
The formula, and why even-money is the trap
A normal bet returns your stake plus winnings. A free (or "bonus") bet returns only the winnings — the token is consumed. Expected/extractable value = Face × (1 − 1/decimal). At +100 (decimal 2.00) that's 100×(1−0.5) = $50. At +200 (3.00) it's $66.67; at +300 (4.00), $75. Higher odds extract more face value but win less often, so the realized value clusters around ~70% of face. Betting it on a near-coin-flip — the natural "don't waste it" move — is mathematically the least you can get out of it.
Source: Newall, Cortis & Torrance, "The value of 'free bets'..." UNLV Gaming Research & Review Journal (2025) — bettors who chase higher odds to maximise free-bet value face higher variance. Newall et al. work a ~67% example; across matched-betting analyses, typical realised value is roughly two-thirds (~70%) of face, well below the headline number.
SCAM 4 "Risk-Free" / "No-Sweat"
The word that got a book fined. A "risk-free" or "no-sweat" first bet that loses doesn't refund cash — it refunds bonus bets, which (per Scam 3) are worth far less than face. So you really did lose money.
$1,000
It loses. You're "made whole" with $1,000 in bonus bets. But bonus bets convert at ~70% of face, so the real refund is only$700
Your actual loss on a "risk-free" bet: $300. The risk was always real.
"Risk-free" meant "you lose ~30% instead of 100%." That's a discount on a loss, not the absence of one.
The regulators who acted — and the limits of what's true
A $1,000 "no-sweat" bet that loses and refunds bonus bets worth ~70% of face leaves a real loss near $300 (the prompt's $575-bonus framing — a partial/percentage refund — lands around a $425 real loss; either way it is a loss). Regulators have moved on the language: Ohio's Casino Control Commission settled with DraftKings for $500,000 (Jan 2023) over "free"/"risk-free" promos that required real-money risk. The American Gaming Association updated its Responsible Marketing Code to ban the term "risk free" (Mar 2023) — industry self-regulation, not law. The New York Attorney General warned that a heavily-advertised "$1,000 bonus" actually required $25,000 of wagering to fully unlock.
Honest limits: these are state actions (Ohio) and industry self-regulation (AGA) plus a state-AG consumer warning (NY). There is no FTC enforcement here, and the federal SAFE Bet Act is a proposed bill, not law. We won't overclaim.
SCAM 5 Cash-Out is −EV
The "take your money and run" button. Early-settlement quotes below the fair hedge value, baking in a second margin on top of the one you already paid. Convenience, priced.
$500
10%
Fair (hedge it yourself)
$500
Button offers you
$450
Tapping "Cash Out" hands the book $50 for the convenience.
The documented margins: 8.5%, 10%, 10.2%
Cash-out quotes you a price below what you'd get by laying off the bet at fair market odds. Newall & Cortis measured the embedded margin across operators at roughly 8.5%, 10%, and 10.2% — i.e. cashing out a bet worth $500 typically nets ~$450, gifting ~$50 on top of the vig you already paid to enter. The button is designed to feel like control; it is a second toll.
Source: Newall & Cortis, "Are sports bettors biased toward longshots, favorites, or both? A literature review / cash-out margins," Judgment and Decision Making 14(5):605 (2019) — documents cash-out margins of 8.5%, 10% and 10.2% relative to fair value.
💸 What this app quietly took from you this session
Skimmed by the vig on "even" coin-flips$0
Lost to parlay hold inflation$0
Free-bet value that wasn't real$0
Given up to cash-out margin$0
Total handed to the house$0
Flip a coin, build a parlay, drag the sliders — every interaction adds the real, documented cost to this tally. Nothing here is rigged; it's just priced.
The one-line summary the app will never show you
A casino has to hide its edge behind a wheel or a card. A sportsbook hides it in plain numbers that read as generosity — "+600," "free bet," "risk-free," "cash out now." Each one is a real, measurable tax: a 4.55% vig, a parlay hold that climbs past 21%, a "$100 free bet" worth ~$70, a "risk-free" bet that still loses, and a cash-out that costs ~10%. None of it requires a single rigged event. That's the trap.
⚖️ A demonstration of documented industry mechanics — not an accusation about any specific company. Play money only: nothing to buy, win, or cash out. Every claim is sourced.