When asked how much I would like to make for a salary, I usually answer their question with a question... "Well, what is the range that you expect to pay for this position? We can go from there." It totally puts you in the drivers seat.
I used to use the "flexible" answer and I found out why that one stinks as well, good negotiators will turn flexible around on you to mean "willing to take less" and it screams desperation... never underestimate the power of a good negotiator, its amazing what they can do to you if you leave an opening.
In any negotiation, you have to make the other person chase YOU, not vice versa. Its difficult because you are the one needing a job, but you have to get the mindset that they are hiring and need you as much as you need them. Make them chase you and your skillset.
I agree, asking for less is never better, leaves you with zero leverage. Bad bad bad advise.