I never reraise with complete air, but I do on occasion when I have a hand that isn't usually strong enough to warrant it.

If I think the raiser is weak for some reason, I will reraise strongly (at least 3x) when I think my hand is behind only if:
- I have position
- it is (or will most likely be) heads up, and
- I have at least some kind of a draw.

My reraises are aiming to make them fold, and if they don't I'll hopefully hit big, or they'll shut down with a weak hand and my hand will have some showdown value.

E.g. I may reraise with 88 preflop from the button if UTG made a weak raise and it was folded to me.

Postflop I will need to think they're pretty weak to reraise with a two-outer, but am more likely to do it with a flush draw.

I will also look at stack sizes. If I think I'm behind and the raiser is a short stack I won't reraise bluff, as they love to go all-in. If there's a large effective stack and I have even a weak draw I'm more likely to do it.

I never 3-bet bluff with air. It's just too expensive.

I don't think reraise bluffs are something you should look to do often. Only do it rarely and if there's a good chance they'll fold. It could end up becoming very expensive if you do it too often and in the wrong places. Never doing it at all is possibly a profitable move.

In terms of non-bluff but non-regular reraising, if I have a hand that I wouldn't normally reraise but I think I'm ahead anyway, I may reraise with it. E.g. if I have AQs and the opponent has raised 22% of their hands or something. If I do this though I will probably be willing to play for stacks with TP against this opponent with an agreeable board. I will never do this with a weaker drawing hand like AQo though.

This is at $25NL.