OP - I'm also Canadian and I've travelled a fair bit in the US (as I was born there, and have family there).
My advice to you is to know your route and stick to it.
We once took the wrong exit in Syracuse, New York, and ended up in a place that did indeed look like a war zone. The buildings were boarded up, some of the traffic lights were broken (which was fine, because we weren't comfortable stopping anyway), the streets were empty of cars, and there were people just sitting in doorways and standing around. We were legitimately worried for our safety.
Now we're extra-careful to research our route.
If you do get turned around, stop at a gas station to ask for directions.
I don't think your concerns are entirely unfounded, but I do believe with proper planning you'll be just fine. Most Americans are lovely people, just like most Canadians.
And for the record... I don't get offended when people believe stereotypes about Canada, either. I think it's funny.