Most hosts won't have much of an issue with content that is lewd, most companies get twisted about child pornography and the like (which they rightfully should). Basically, understand the location of your server, and understand the jurisdiction of law in which the host will fall.
There are some hosts that outright will disallow that sort of content -- but realistically if they don't know, what would they do? (Nothing is the answer) Most don't have the ludicrous funding to have people go through and ensure every server they own doesn't contain pornographic content. They may try to use an artificial intelligence to do such a thing, but it's not likely, and besides, the last one I knew of that could "detect" porn was based on the lighting in a given photo or video.
All that being said, most hosts, as malmon said, don't give a fuck. As long as it's not something unreasonable. As a slight note, there are some jurisdictions in which specific classifications of pornographic content are disallowed, for example rape (even if it was done by actors and actresses and all were consenting), which is something you will need to be more careful with. Again, just understand the laws of the location the server.
On another note, you could host your own server in your own home. Security threats may show themselves, but depending on how you set your server up, you can alleviate them. My previous personally owned server, for example, had its own separate internet connection provided, own router and modem, server, completely separate from the one that I would use for my actual computer. More costly, yes, but more safe in that aspect.
Perhaps it's not realistic to buy another service for one computer, in which case you can host it on your own pre-existing personal-use network, but regardless, by going the way of hosting your own server you can dictate what goes on the drives in the system. Keep in mind though, that just because you own it doesn't mean that you can disregard the laws that you live under, good way to get arrested.
TLDR; most don't care, read TOS if you feel paranoid, follow laws