In the right situation, a cliché can work well and even be humorous. But
most of the time, they're just annoying. The damsel in distress. The evil dragon
terrifying the countryside. The knight in shining armor. The vengeful hunter. On
and on, ad infinitum.
Of course, we're not saying that you have to think of something totally original that's never been done before. That'd be nice, but that's also very difficult. ^^ Not to mention, who can say what's been done before and what hasn't? But what you can do is think of something that's been done less than others and is semi-creative, or perhaps a new twist on an old gag. Like, say, the virgin losing her virginity on the altar rather than the virgin sacrifice. Or maybe the valiant, gallant, skillful knight--who also happens to be completely blind. Something like that.
And now, just to make things easy for you, is a list of overused clichés in bullet form. Mind you, this list is far from complete. There are far too many clichés out there to be named.
There are exceptions to these clichés, of course. Some of them have been done and done well, and as I mentioned earlier, there are plenty of ways to twist them into something more original. All it takes is a little creativity and imagination. It's much more fun to play something original than something clichéd, don't you think?