Why are hookers so despised among a lot of Americans?

I'm not American myself, so this is why I ask this question. Many times when I'm surfing on American forums and people talk about prostitutes, they seem to despise them like crazy. Also, I've made several experiences in real life where I talked to Americans who condescended very much towards prostitutes. Already the fact that promiscuous women are often called "whores" on forums such as this one speaks volumes. Not only do many people obviously find it okay for guys to be promiscuous but not for girls, which is a huge double standard, but also would they use a slang term for "prostitute" as a swear word for promisuous women. The fact that they use words such as "whore" for name calling means that they consider prostitutes to be something very bad, someone you should hate and condescend to.

Now, I wonder why that is. Prostitution may be not be the most socially accepted type of work there is, but it is one of the oldest jobs in the world. Moreover, hookers probably work hard than most other people. Anyone can sit behind a desk and act smart but how many people can have multiple times of sex every day with people they don't fancy and still act as though they'd be having tons of fun? I don't despise prostitutes. In fact, I have a great amount of respect for them. Way more than for slick bankers and sneaky lawyers in expensive suits. I believe hookers should receive much more credit for the job they perform and for the social discrimination they put up with.