Wow, gum is a nightmare! I don't think it's always malice. I've found that some people live in ways that are incomprehensible to me, and recognizing them is nearly impossible. I knew someone who was fastidious about every detail of his person, so it was shocking when I saw how he lived: stacks of old food in every room, a bathroom that was grimy and smelly with who-knows-what, just ... filth. Go figure. But good luck!

I rented out my house--- ten broken windows, glass in front of oven shattered. What was worse was the amount of dryed snot on the walls. that stuff can't be scrubbed off. Had to repaint every room except the kitchen. It was filthy and they left a so much moldy bagged clothes and other assorted crap. I had a four bedroom house. I just had to say to myself---There is no meth lab or dead bodies in the basement .

Some people are just mean, like those who scratch your parked car, do the chewing gum, break the toilet and windows, furniture, those who vandalize, cut, paint with markers the seats, walls, anything they can

Gumout
[googone.com]
The ice works suprisingly well

Keep deposit small claims court to get anything else due

You get to keep the security deposit and clean everything up. Congrats.