The Girl in 304, by Harold R. Daniels. Cover art by Walter Brooks. 1956.
On the back cover:
Standing in front of her mirror in Room 304, slipping on her yellow dress for the Sunday evening's work, Lucy Carter wearily hoped the bright color would be the bait she needed for a successful night.
Sometimes, though, it could hook the worst sort of fish...like Lt. Cox, whom she'd refused to pay off....
Still, these were the risks of her trade. But when Sheriff Ed Masters found her the next day in the weeds of the Georgia swamland, the risks were over for Lucy Carter...and just beginning for the man who had ended them.