IMO there is nothing inherently self-disrespecting about sex work. I see it in the same vein as someone providing a relaxation massage - you are using your body to provide physical pleasure to someone else who is paying for it. If we decided that all masseuses were disrespecting themselves and then spread this idea throughout society, chances are you would see people in the pub high-fiving their mates and talking about the masseuse in a derogatory way. I don't think it would be fair in this instance to blame the masseuse for the disrespect of herself - or indeed of women in general - just as I don't think it is fair to blame sex workers for the lack of respect that society shows them. I also don't think it's fair to extrapolate that and blame them for contributing to the lack of respect for women in society -lack of respect for sex workers is a symptom of lack of respect for women, not a cause.