Francisco d'Anconia said:
Most of us heard of them, many profess to use them; but are they really successful and does it depend on your age?
They are useful under two circumstances.
A) You know how to properly use them. Most people here misunderstand them and think any insult is a neg. Telling a girl she's ugly is not a neg. Telling her she's stupid is not a neg. Acting as though you think a girl is a vvhore is not a neg (I've seen each of these mentioned on this site in posts where people called them negs). Those are just plain insults, and they are quite obviously so to the girl.
A neg used properly is just to make the girl see that she thinks she's more important than you do. You can't sound like you're intending it to be negative or it will backfire. Think of a neg more as a back-handed compliment. You don't use them as openers if you expect to be successful, you need to feel the girl out first. The reasoning being....
B) You use them if the girl thinks she's above you, or too good for you. If the girl is already self-conscious about something and then you go dig her on it, you're just going to put her in mega-defensive mode, or she's going to be embarassed about it, which will cause negative feelings that with resultingly be associated with you. Not good. But if the girl thinks she's super hot sh!t, you can bring her down a notch with a good neg.
Some examples of negs I've used that seemed to work and open a girl up after an initial cold response.
"Hey, those are nice earrings. When I first swa those at the dollar store I thought they looked really good for how cheap they were."
"Oh, that's a Gucci purse huh? Funny, I just expected them to look a little.... I don't know, more expensive in person."
After seeing a girl stumble a bit while standing...
"Maybe you should stick with flats when you're drinking instead of such big heels."
"Do you have a tongue ring or something, because it sounds like you're talking a little funny. No, it's cute though..."
I don't think it's dependant on age at all, it's about you using them the right way, and only using them on the right girls.