I like your hair - is that your natural colour?

almost, that's a qualifier, but there is no disqualification involved in the qualifier

a neg is a qualifier that dis-qualifies you or her, so that you are not framed as a potential suitor, so if it was (it's like qualifying her from the context that you are not sexually interested)

you: I like your hair, it would look even better if you put extensions in it
= neg

or

you: I like your hair, is that your natural colour?
her: blah blah
you: ohh, well it still looks really good anyways
= neg

what he said ^^ i personally like the "would look better up/down"... they try to fix it and what not, gives me a good laugh as well

thanks pumpington and mattylife, really good answers from both of you.. Im pretty confident i understand negs now

Try "have you ever had blonde hair"? Unless she has it now then substitute for "red"

The girl presupposes that you have had the conversation in your head "I would be attracted to this girl if she was a blonde so I will find out if she has ever had it as it makes her more likely to go back that colour then I would be interested in her.

It's a neg as in: She isn't attractive with her current hair colour.
And a disqualifier in that: You're interested in blondes, which she isn't.

The good thing being you haven't actually stated that, she has just inferred it so there is full plausible deniability.

melodical, i like that as well.. however what would your response be if she then said "yes/no" ? it seems to me like the neg wouldnt be fully completed until you come up with some sort of suitable response to her answer?

I assume if she said "yes" then you would say "you should have kept it that colour, your hair still looks nice now though" OR if she said "no" then you would say "you should try it"