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Just as there can be lawsuits for discrimination based on race, religion, political affiliation, etc - I don't see why discrimination is allowed to be directed at sex workers. Being a sex worker surely falls into the same category.
They get discrimination from everyone: feminists, media, employers, hypocrites - mostly circular logic along the lines of 'I don't respect your choice to be a sex worker because if you choose to be a sex worker no one will respect you!'
One of the most famous porn stars out there was having a Wikipedia battle where some asshole repeatedly included her real name on her Wikipedia entry, claiming it was 'in the public interest to know, therefore deserves to be in Wikipedia'. The porn star repeatedly tried to remove it in the interest of her own privacy and safety.
Just treat them with the same respect that any other human being deserves and there's no problem.