For starters, most retail outlets have policies against leafleting in their parking lots. (Wal-Mart, Sears, etc. will not allow any type of solicitation on their properties) I'm sure they would feel no different about someone putting stickers on windshields.

The OP was talking specifically about finding a sticker which would be hard to remove. While a leaflet under my wiper arm would merely annoy me (and immediately get thrown in the trash), a sticker would irritate me to no end, as I would legally have to remove it before driving. Any obstruction to forward vision is a safety violation. This being the case, I would be forced to call the police and file a complaint.

Leaving an animal in a car is not against the law in New York, but animal cruelty is. I prefer laws remain that way. Why? If you need to pick up a quick item on the way home from the vet's office, or another instance where an animal would be in the car with you, no problem. No harm is going to come to Lady in the 2-3 minutes it takes me to go into the supermarket and grab a gallon of milk. If, however, an animal is left in a car long enough to cause distress, it would be animal cruelty or neglect.

I have many issues with precision targeted laws in general, but that's another discussion.