Over half of ds's (6 years old) friends come for playdates and break/wreck something - I've always assumed that's just boys for you but it's odd to me because ds is boisterous but never an intentional wrecker.
One of ds's friends has to do something devious every visit. One time he hid the key to a cupboard behind the loo (thanks mate!) Another time he poured blue play slime (it had been stored out of the way!) onto ds's bedroom carpet and hid it under loads of other toys, when we tidied up at bedtime it had soaked into the carpet and ruined it.
I've never mentioned it to the mother, she smiles proudly about this kind of behaviour generally as if it's all a sign of how intelligent he is rather than how much of a little b !