Where I live, many bars have 8 line slot machines that are ostensibly "For Amusement Only" but they pay out when people win (and if they know you).
If you win too much, you'll be banned from playing.
Just knowing when to raise your bet does a lot to tip the odds in your favor.
I actually did something like that once. A store I visited put a link to a survey on its receipt with an offer of $10 off any one item on completion. I completed the survey on my phone, which displayed a barcode they could scan and selected a sub-$10 item. The receipt for my free item had a link to a survey....
I limited myself to a few items I actually had a use for. They would have been well within their rights to cut me off after a while, but certainly not to have me charged with a crime.