To me personally they show a lack of originality and therefore force me to question the intelligence of the person using them. 愛
I think it depends how much swagger and bravado you can deliver them with. I remember back in the day I used to walk up to guys at the bar, sit in their lap and say "Do you mind if I sit here while you buy me a drink?" Only once did anyone not buy me a drink. That guy laughed loudly, asked me if that ever really worked and made a comment about the brass ones I must have and we ended up chatting. We're still friends twenty years later.
Deliver them confidently and somewhat originally and they might work. You really need to be convinced that it's going to work; the audacity is often the funniest and most endearing thing. Just look at OGS's (might I say amazing and a must-try?) method. It's so temerarious that it exudes more than humour; it shows a bold personality worth interacting with. Just make sure that any such behaviour is welcome in some environments, it'll be taken very well. In others, it may offend, upset or even anger the object of your desire.
OGS and Aussie792 summed it up well. I'd add this, though: You have to know who you're talking to. Even if it's a complete stranger, take note of what they're wearing, how they're acting, and what accessories they have on (most folks like to express themselves, and many will enhance their better features; people tend to respond positively to you, if you acknowledge what they hope others will, especially the subtle things). So, if you notice somebody with a nice scarf on, say: "You look fantastic on that scarf -- I mean, that scarf looks fantastic on you!" You're showing a friendly flaw here, which lowers the other person's guard, by displaying a little bit of well-intentioned silliness. Confidence is nice, but sometimes it can be slightly intimidating, even pushing another away if it comes on "too harsh". Make somebody smile/laugh, and you're practically in -- just don't fuck up from this point on. As I tell folks, laughter is the individual's drawbridge. Get them to laugh, and you're golden.
The lines don't melt my panties off, but they break the ice. If delivered correctly they can start a conversation. That's all. Points for geeky and really dirty ones.
I have one delightfully cheesy chat-up line that I could use actually, but I can't tell on here without revealing my name, as the line includes it.
It's much better to personalize your words so you're treating the other person like an individual, not a dartboard.