Cleaning isn't the problem. It's the sexualizing of what is otherwise not a sexual activity. Normally, sexualizing your maid who is there just to clean would be seen as highly inappropriate, and the maid may even have grounds for legal action if the sexualization took a bad turn. If a normal maid was cleaning and the employer followed her around leering, she'd be uncomfortable. It may even be harassment, depending on the severity.
By adding the sexual element to the otherwise non-sexual act, it is specifically sexualizing it for the purposes of gratifying the viewer (and hey, maybe even the maid too). That means what is being sold is no longer just cleaning, but sex, and it's immediate, personal, non-removed sex (as opposed, say, to watching porn or reading an erotic novel). The person before you is nude specifically so you can sexually objectify them right there in the moment in that context. The person is selling you the right to do that, to see them and imagine having sex with them (okay fine, maybe there's one client out there who's in it for the "art" of the "nude form" but really, the point is to see the person naked and be able to imagine having sex with them).
That's where the exploitative nature comes in and where it comes alongside prostitution. The person is selling their body for viewing. And it's not just casual: cleaning involves a lot of bending, squatting, and other poses that are going to readily lend themselves to a wide array of views.
It is possible to argue that the exploitation goes both ways, insofar as the cleaners are gaining more clients by exploiting their sexual needs. But there's definitely sexual exploitation going on.
It's submissive in the very structure of the financial relationship. The nude cleaner is there to serve the client. There may be rules about what services are permitted, but make no mistake, the power structure entirely favours the client. As above, the likely poses will enhance the submissive nature of the entire deal: if someone is paid to be naked and bending over to clean a toilet, there's no way you can argue that that's a dominant or even equal position to the one who is paying and watching.
It would be interesting to see how perceptions of this would change if the cleaner that gets assigned to a client's house is not their preferred gender. If you're going to argue that this is simply cleaning with nudity added, then is it okay for the company to send a naked man to clean a heterosexual male client's home?
Also: I never said it was evil. Please don't put words in my mouth. It negates your entire argument.