Hi Sofia
It could be that they are opening new profiles, go through a friend or just don't care.
There are things you can do to minimise the risk of bad guest
What sort of checks do you carry out with your guests? Do you
1. Make sure each guest has a verified profile
2. Talk to each guest in advance of booking to understand their plans and why they chose your place to make sure there is a good fit
3. Make sure they have a full photo and completed profile
4. Have a deposit
5. Have comprehensive house rules
Bad guests tend to be put off from having these in place so it minimises your risk