I think you are talking about Live Chess games at longer time controls, such as 15 mins per game + 10 secs per move or so.
Opponents who "fail to find the resign button" may risk that you will not find it interesting to play a second game against them, and they sometimes may give the impression that they felt that this game has been a particularly crushing win for you, so you may even take this as an indirect compliment to your strong play if you will.
Often, you just may not be disturbed in any way by such an occurence. For one thing, you have started a game at that time control, so in a certain way, it is just up to the opponent how he uses his agreed thinking time. If during a game, you have the leisure of getting yourself a nice glass of water, do a nice little stretching exercise, ... this can even be a nice thing :-)
If I see that an opponent may be letting time out his last 20 minutes or so, I may just use the occasion to have a look at the chess.com forums, check one of my vote chess games I am discussing and analyzing in, check one of my online games and analyze it a little, have a try at the daily puzzle, ... or similar things. (I will leave the live chess board visible in a separate window, or I may just know that I will hear it when there is a move in the live chess game.) Chess.com has the advantage that in such a situation, unlike in an over-the-board game for example, you are certainly not lacking nice things to do in the meantime :-)
Hey on couple occations ive noticed players just logging off, leaving computer or dragging out time when they are on a forced loose. How can one deal with this? Boring to wait for 20 mins to next match cuz of some moron ruining for you.