The funny thing is, Christians talk about winning the lost. It's touted as the Brass Ring of Christianity.
But the catch is, Christians expect that all the lost must come to church (or only other Christian-approved places) in order to be saved. Too bad for anyone else who happens to be wandering around in non-Christian-approved places, or for people who have been deeply hurt by supposedly Godly people and are deathly afraid of anything having to do with organized religion. I'm always amused by the fact that Christians somehow seem to expect the lost to come to them instead of the other way around, which is an example that Jesus Himself gave.
I think that as others have noted, you have to know yourself and your own intentions. I have one story in particular I'd like to tell, but it's fairly long and I'm not sure it would catch anyone's interest, so I'll save it for another time.
I will say though that I was involved with a church that wanted to start a group that went to such places just talk to people, get to know them, and, if it seemed to go in that direction, invite them to church. I was very excited about this but unfortunately, the group never took hold, probably because of many traditional Christians who lived and died by the "Never Set Foot In Such a Place, Ever" Creed.
Now I'm certainly not advocating going to nightclubs if you have a problem with drinking, the party life, or going to such places. It's all about knowing your limits and boundaries. If you know those places are trouble for you personally, don't go. I'm also not saying we have to go to such places in order to win the lost or that we can excuse reckless behavior every weekend by trying to call it working in the missions field. But God may have purpose for a Christian who goes to such a place.
In 6 years of college (4 undergrad, 2 grad), I can count on both hands the number of times I went to clubs, and the primary reason I was asked was to be the DD (designated non-drinker who gets people home safely.) I've never been much of a drinker and people go back and forth between teasing me to bits and asking me to cart them around.
Now I know some Christians will say, "You should never endorse their evil, sinful behavior to begin with!!! Why go to a place like that with them and encourage such heathen behavior!!" Well for one thing, I tend to like the music at clubs. And, every now and then, if I can bury myself in the midst of a crowd, I even like to dance.
One time I went there was a girl in our group who wanted to go home with some random guy she met at the club. I told her, "No way. We all came here together, we're all leaving together." It wasn't easy to stand up to her, as she and I both had very strong personalities. But, sometimes people who put up a fight are actually waiting, and even hoping, for someone to make the effort to fight with them a little. I told her, "If you go off with this guy and something bad happens to you, there's no way I'm going to carry that around on my conscience (when I have a chance to do something about it.)" Needless to say, we all left together and at the same time that night.
People are going to do what they're going to do, regardless of what our own opinion, and I'll be the first to admit there's a fine line between enabling and taking a stand.
But I believe God had a purpose in my going along that night (I usually decline so many times that they just stop asking.) I can't always prevent or protest what people might decide to do. But my hope is that maybe someday the people I went with will look back and say, "When I was young and making bad decisions, a Christian cared about me enough to look out for me even during my worst times. I want to know more about why they believe the way they do so I can do that for someone else, too."