What are your general thoughts on players who overbet the river? I realize this is player and situation dependent. What do you give the player credit for?

Is it always the nuts or a bluff?
Is it usually the stone cold nuts?
Could it be a weirdly played marginal hand?
Do you do it?

I don't use the play very often so I'm interested to hear when and why u guys do it.

I'd say that against all but the bravest/best/dumbest/smartest you'll be looking at the nuts or near nuts like 99% of the time.

Rounders, overbet the pot to make it look like I'm bluffing, he plays back, blah blah blah Mike McDermott.

When a decent player does it I am really worried, I rarely see an overbet bluff at least not any that I have seen called

I think the overbet is a great play, if used correctly.

there are a few very good areas where an overbet becomes valuable

like triple B said, when you suspect your opponent has a ahnd that they can't fold, but are also unlikely to raise/reraise - such as the J on the 6789T boartd when you hold QJ.

or when you hold either a hand like 44 on a KK442 board and you suspect your opponenet holds the K but isn't very aggressive, or if you hold something like K5 on a KK445 board in the same situation.

After that you have the situations against people who like to pick off bluffs. This of course is only valuable if A: the player hasn't seen you make this play before, and B: you have an aggressive image in his mind. Obviously this is when you are positive you have the best hand - a set, maybe top two, the nuts, whatever, just as long as you trust your read to be right here.

That is of course the most common place to use it, and like most of these guys are saying, it's almost always the nuts/near nuts (or at least a hand that wants their stack in). It rarely works against good players, and works even less against a good player who's seen you make this move against a weaker player.

This leads to the last good use for the overbet - the far less used overbet bluff. Since I use the overbet value bet against a bad player, i'll use the overbet bluff against the good player. As everyones pointed out, the good players simply realize "overbet = hoping value bet". They simply can not call without a monster themselves.

This isn't to say that this is something you should do a lot, and in general can be a dangerous play. the entire play revolves around the notion that you opponents firmly believe that overbet = nuts. the more often you make it, the more likely they'll start to wonder if that read is correct. Of course, once they call you here, you have a metagame advantage, but that's another argument all together.