Is it fair?

If the newer they are, the sooner I'll point to the clock.

in a way by not saying something to your opponent, it might help him in the future. in the next game he might pay more attention to the clock than he would have if I'd say something. lesson learned.
if he got away with being careless he might do it over and over. no lesson learned.
he might be up against somebody that isn't a saint in the next game /tournament.

if the same thing happend to me I wouldn't have any hard feelings at my opponent or think any less of my opponent. It would be my mistake. I would only have myself to blaime. Of course I would be irritated but only at meself.

I don´t tell my opponent directly but use the time to check out the position more closely. When I am done with that I stand up and take a walk. This usually upsets my opponent and makes him realise his error ...

I will usually wait for about 30 seconds to a minute, and if my opponent hasn't corrected his/her mistake by then, I will let them know. I'm also more likely to remind the person to change their clock if they are a weaker player who hasn't had very much experience playing with a clock. If they're a stronger player, they really should know better. I suppose it is perfectly legal to simply sit there for as long as it takes the other person to realize their mistake, but since I hate it so much when people do it to me, I don't really like to do it myself. Basically, is it legal? Yes. Is it nice? Not especially.

How would that work?

You don't see that they haven't hit their clock either, I've done that before.

Not telling is one thing, but them putting on a show pretending it's their move would make me want to use my opponent's head to stop the clock with.

woodshover:

It's not like I'm making a huge thing out of it. I'm doing it subtlety. It's worked in quite a few blitz games.

This. Show some sportsmanship and alert him to the situation the first time it happens. Beyond that, the effects of their continued negligence fall on their shoulders so take advantage of your opponent's weakness.

Though, winning a game only due to that sort of mistake is a bit weak.

I always tell my opponent if he forgets to press his clock. I do have a problem waking up my opponent, I'll let a TD do that.

defragc

If your opponent leaves a rook hanging, won't you take it?  If they hang mate, won't you deliver it?  If I'm playing in a club and my opponent doesn't punch the clock, I'll remind him every time, no matter how many times that may be.  But in a tournament, as I stated before, I'm under no obligation to warn my opponent of impending doom.  And besides, I consider it an offense to the other players in the event to warn him--if he does something to lose the game, let him lose and learn like the rest of us.  I have a warm heart before and after the event, but never during--you gotta treat it like a knife fight; no quarter asked or given.

having a poker face in chess is part of the  game.
why punish your opponent for something that you didn't do. you only have yourself to be irritated at.

These are all centered on moves and outmanuvering your opponent to deftly defeat them. Beating your opponent only because he forgot to hit his clock, especially if he was a better actual player, is weak, period. But a win is a win, like I said. They made the mistake, not you.

I've never played OTB, but it seems they're resorting to silly little tricks to make up for lack of chess ability. Having a poker face during actual play is a different matter completely.

you should try otb. ok besides that is important to maintain score card and maintaing the clock there are no silly tricks. Like Bobby Fischer said "play the board ".

No disrespect intended, but could you please explain how you justify this seeming double standard? I agree that not telling one's opponent about his draining clock is fair (i.e., equitable), but I don't understand how it can remain fair when you base the decision to tell him on 1) whether you dislike him or 2) whether the game is critical/important.

I say let the clock run down. It gives you thinking time and the advantage in time.

It's fair.