As the law goes, any violence, damage or threats, will have you, even as owner, in front of the courts and you can end up in jail.  It is not uncommon for the okupas/ squatters to call the police and denounce you.  Three denounces in Spain and you can be deported even as a frustrated and legal property owner.

You have to pay all the bills or this can cause you further issues and legal costs.

Squatters may cause thousands of euros worth of damage and are more likely to do this if they are offended and you have a very difficult time trying to prove they caused the damage adding to the frustration and costs.

Its complex and it is not like other European states, many judges are left leaning and will side with the criminals.