I'm sure he even has a song named Streetwalker.
It's a love song, there's nothing negative about women or prostitutes in that song.
I want to clarify that the issue isn't that he writes about prostitutes, it's that he repeatedly writes about such women using negative stereotypes which sympathizes the male perspective without holding them in any way responsible for the scenarios he is critiquing the woman of.
Repeatedly? You can probably count them on one hand. Also, have we considered the possibility that the male in the song might not actually be the one responsible? In real life, Michael was falsely accused of being the father of the children of women he never even slept with, and that's what the song Billie Jean is about, not about a man refusing to take responsibility for the child he did father. I think the line "Cause the lie becomes the truth" makes it pretty obvious that Billie Jean is lying about him being the father. And the line "Billie Jean is not my lover" makes it pretty clear that this was NOT a girl he was sleeping with. When he says "She called me to her room," there is then nothing to indicate that he did go to her room in response. Sounds to me like it's just a girl he danced with, she wanted to sleep with him, but he did not, then she made up lies about sleeping with him and him being the father of her child.
Same thing with Dirty Diana. Where is the proof in that song that he actually slept with her? Michael tells his girlfriend to unlock the door, meaning that he intends to go home that night. Then Diana tells his girlfriend, "He's not coming back because he's sleeping with me," but when did Michael actually agree to sleep with her? The whole song is Michael saying 'I will not sleep with you no matter how hard you try'. So who was telling the truth about whether or not he ended up sleeping with her, Michael or Diana? If Diana lied to Michael's girlfriend about Michael sleeping with her, then wouldn't Michael be justified in portraying her as the bad guy and himself as the innocent victim?
In the song Dangerous, the woman again tells Michael's girlfriend she slept with him. But was that the truth, had she actually slept with him at that point in time? In the verse just before the bridge, Michael says, "You and your manipulation, you hurt my baby", then the bridge seems to indicate that she actually managed to seduce him, "And then it happened, she touched me,..." but that was AFTER she already told his girlfriend he slept with her. Meaning that she lied to his girlfriend in order to cause her to break up with him so she could take him for herself. I think it's fair then for Michael to portray her negatively and hold her responsible for destroying his relationship with his girlfriend.