Definition of reverse float
Usually, a float is a bet made in position. A player who has the lead checks out of position while we are in position. We have the information that he checks and we make an opportunistic bet, no matter what we have. This bet is a float. But a reverse float is when you float out of position. It's a bit like a probe bet, but after the player in position has bet. Simple situation: Button opens, and small blind calls. Small blind checks, button bets, small blind calls. The turn is revealed. The player in position SB decides to go for a donkbet (a bet out of position without the lead) for the reverse float.
What is reverse float worth?
Reverse float will embarrass you more often than you want to be embarrassed. In our example above, the player in position showed no sign of weakness and the player in SB position bet. Also, good position players will interpret this play as a sign of weakness, or even a bluff. You will rarely have an easy time with a reverse float... Unless you make this play knowingly and have the perfect opponent for it, it is a play to avoid.