I lived in a bland, boring commuter suburb of Paris for 2 months to improve my French. Completely different to central Paris which I came to hate as much as the French. Even my poor French trumped people's willingness to switch to English, and many people in the suburbs speak very little English. So it's possible to get immersion even in a city like Paris.
I strongly dislike Paris - the city - not Parisians or non-Parisian French living there.
I dislike it the same way I dislike London. To someone like me, more at home in the countryside, it's just a noisy, sprawling, unclean armpit of a place. My opinion (and one shared by many French people I spoke to) is that Paris is no longer French in the same way that London is no longer English. They effectively operate as city states.
I really dislike this cliche that Parisians are rude. It is absolutely untrue, and usually the product of tourists not understanding French culture and inadvertently causing offence. It is also a product of people only visiting the hellhole tourist areas. Like most French people I wouldn't dream of going to those areas unless you paid me!
As an unbias observer (neither a proper local, nor a proper tourist) I can definitely say that the rudeness of tourists far far outweighs the rudeness of the locals. In fact, I don't recall any direct rudeness from locals at all. On the other hand, seeing tourists behave in a disrespectful manner was a daily occurrence.
And at that time I had been travelling to lots of countries for years, and I never had any trouble communicating with people. Big cities, villages at mountain tops, desolated island towns. People were nice everywhere. Except for Paris.
If that has changed for the better recently then that's truly good news.
I would guess there might be a few motivations for people to do this though, not necessarily just rudeness. Misplaced helpfulness, wanting to save face by not switching languages back, practicing English, who knows?
(What's really funny is when they finally give up and revert to French and then address a question to me - only for me to shrug with embarrassment and tell them I don't speak French.)
I'd argue that there is a surprisingly homogeneous distribution of horrible people throughout the big cities of the world.
As a native French speaker travelling in Montreal, I often found it easier to talk English with French speaking people, to my great shame.
I recall a simple transaction with a cashier in a supermarket, and having her repeat the simplest things (like "hello") a couple time because I had no idea what she was saying or if she even was speaking French, this was awfully embarrassing.
Although I agree, Parisians are asshole.