It could be worse. We had one tenant who decided that she wanted more heat in one of her radiators, and her dad was a "plumber" (self-described), so he came and fixed it. Except that the stupid cretin opened up all the lockshield valves and wrecked the balancing of the system. And then she complained that several of the radiators were stone cold, and what were we going to do about it?
It got worse. Her dad then sent us a bill for his unwanted attentions. Including VAT (which he wasn't registered for) and the cost of parking his car while he was screwing up the central heating system. Dream on, you goon. Just be grateful we haven't charged you for the costs of fixing the trouble you've caused us.
Then it got worse. The next tenants installed a double powerpoint in the bathroom, so that they could put their washing machine in there. Three feet from the bathtub, and as dangerous/illegal as you're ever likely to get. And the other power socket? It carried the plug for a halogen reading lamp that they'd picked up in some junk market, and which had been nailed to the wall just above the washbasin.
Give me the "can't wire a plug/electricity terrifies me
" brigade any day. They don't kill so many people.