Made a $300 deposit to bet on a soccer game this wednesday, home team for 3.09. The line wasn't arbable or anything, it was actually a 94% market.
When I tried to bet them, it said "max bet is $50" so I shrugged and tried to bet that amount (needed to clear the bonus). The site then told me "odds have changed" to 2.95!
Incredibly unethical in my view, and really really dangerous if you're an arber.