I've see it in at least one big chain T&C, along with a few other don'ts. At the time I was looking into making a complaint about a member or staff.

I knew I wasn't off track thank you for this.

Am quite sure stag and hen parties cause more problems than prossies lol.

They do and they get banned. I was kept awake by noisy stag and hen nights which disrupted several floors, they were removed, hotel removed charges for some 'extras' and told me those guests are now banned. That didn't help those of us who had to sit in a classroom on a course the next day.

If they want to kick you out, hotels/apartment companies can find any reason under the sun based on their standard t&cs to justify their decision. Depends on the particular t&cs but I am sure they can find something and have their backs covered. As long as you are noticed it may be for non 'appropriate' conduct, causing 'offence' to other guests or staff according to their 'reasonable' opinion, even on the basis of health and safety for not identifying and registering your visitors. They will also have legal resources available.

Harassing you is unacceptable but you also need to be careful of how you conduct yourself from the moment they give you notice, so that at least they can't object to any complaints about that.