I lived in Montreal for 6 six years, as a student and for my first job. I speak a bit of French, but not much. One day in Place Ville Marie I was getting a coffee at Starbucks. I accidentally bumped into someone in line, and I said "sorry". He snarled at me angrily and said "Get out of here, go back to Toronto". I don't think I had never been to Toronto at that point in my life.

Mostly that does not happen. Mostly people are okay if you try to speak French. But if you slip up or bump the wrong person, your English can certainly make you the target of hateful and mean language.

There is also a forced, legal "racism" against language, in that it can be prohibitively difficult to start a company in English. There is a systematic approach where the government and the locals will make your life more expensive, more complicated and less likely to succeed unless you do fully understand French.

Edit: That said, I love Montreal. It's probably my favourite city in North America, I miss it tons and tons. I live in the Bay Area now, but feel like Montreal is my home and I can't wait to go back.