Red flag when you look for online companions: what do you never ignore?

I'm talking to two people for a trip to Morocco. The conversation is pleasant, but one always avoids the video call and wants to book an apartment only intact to him; the other often changes budget and program. I don't want to be suspicious of everyone, but I don't even ignore important signals for fear of seem rude. What verifications do before sharing reservations, cars or rooms with someone known online? I am interested in a comparison based on recent experiences: indicated travel period, what really worked and…