Homeowners vary in how they feel about having sitters have guests over. My husband and I house sit full time, mainly internationally–barring the Covid times–and the chances of anyone coming to see us is very low, so it isn’t something we ever ask about upfront as a general question. Most of our friends and family are not the traveling types!
We house sit in NJ for extended periods to visit with friends and family as this is where we are from originally. Many of these HO’s have said we could have guests over. We never asked them about this, but I imagine they thought to offer since we know people in the area. And we appreciate the gesture, though in most cases, we tend to meet people elsewhere.
There have been two house sits where the same friend decided to come visit me. In the first instance, the HO had mentioned it was okay if we had people come visit us when we first got there–of course I checked with her again before confirming plans. She lived in Bali.
The second instance, my friend was going to be about an hour away vacationing with some family and said she could extend her trip a few days and then come stay with us. I asked the HO if this was okay, and made it very clear that if it wasn’t it was totally fine.
I got a pretty relaxed vibe from her, so intuitively I felt comfortable asking, and I got the sense her response saying it was OK was genuine and not something she felt pressured to say because I asked.
In your case, where there is no definite plan to have a guest, but something that may be a possibility, you could ask HO’s how they feel about it just in the general sense, should the possibility arise. You may also put something to that effect in your profile, stressing that if this was not okay with the HO, it is totally fine with you.
If you know for sure a person would want to come visit on a particular sit, it would be a good idea to mention that ahead of time, probably right in your application so the HO knows right away how many people may be staying there.
Again, homeowners vary a lot in how they feel about this. By mentioning even the possibility of having guests over in your profile/application, you may run the risk of some HO’s deciding to pass on you as they don’t want to be put in the position of being asked and then having to say ‘no.’ Or being asked and saying ‘yes’ even though it makes them highly uncomfortable.
You may also find some HO’s address this in their response to your application, and if they say that having guests wouldn’t be okay, you should honor that request and not try to convince them otherwise. You don’t strike me as someone who would do that based on your post, but I have seen HO’s say they got some pushback about this from sitters and that highly surprised me.