Yes, I have. And I currenty am.
There's two reasons why I do it or have done it.
First, I'm giving the game my 3 session test. If after 3 sessions the game sucks ::slaps hands together:: I'm out! You really can't judge a game on its own merits until you've given it a chance not to suck. The first session it's mainly about meeting people if you don't know them, getting a feel for the rules, the setting, the scenario, whatever. The second session is a little more about what the game is going to be like, but you're still making adjustments. By the third session, everyone now is pretty well set into the situation and you can pay total attention to the game itself. Either it's decent, good, or awesome! or it just sucks.
Second reason, it's a good friend and I want to support him. I'm playing in a good friend's Aberrant game. Now, I'm not a fan of super hero games. I think they suuuuuuck. But, I give my friend the benefit of the doubt that he can make it fun and possibly change my opinion. Well, it's fun sometimes, but he hasn't really changed my opinion. I keep playing mainly because I like to hang out with him and the other player who is also a friend that I don't get to see very often and since it's only every other week, I don't have to commit too much of my time to it. So I stay. At least until there comes a day when the suckage outweighs the friend factor.