[bones]

This seems like a pretty straightforward guideline for deciding whether to be in this bet:

If you think it's possible that someone besides gravy will be playing -> don't make the bet.

If you think gravy is a favorite to win the bet -> don't make the bet.

If you trust gravy to play on his own and think he's a dog -> make the bet.

Seems exceeding simple to me. If you think it's possible he could be cheating, just don't make the [censored] bet, but don't drag his name through the mud for no good reason other than it's possible