I had a squirrel come in the house when the back door was open and it chewed the bottom edges off a row of about five books on a bottom shelf. I'd thought it was funny when it was only coming in as far as the window by the door, and the dog chasing it back out, but it managed to get way inside the house unnoticed to reach the books, one of which was rather valuable. I still like them, but between digging bulbs and getting in the house to look for nesting materials, hard not to regard them as little bastards too.
They're usually very territorial and only two large grey squirrels to a neighborhood (plus transiently their babies which have to go find their own territories after they get through adolescence). But between all the birdfeeders in the neighborhood, & Sue next door feeding them corn, we've got three big dreys in a one block area, and two adult squirrels to each drey. That's beginning to be a handfed-in-the-park density, too much food lessening their territoriality.
Sue feeds them whole raw corn cobs. The excesses they were planting all over the neighbrhood, so corn was growing in every sunny spot, then the squirrels harvested corn they planted themselves!
So they sway back and forth between awfully cute and awful nuisances.
-paghat the ratgirl