It's not that they pretend, they really don't speak English ;-)
More precisely they have some notions of English but 1) they won't understand a native and can only pick a few words 2) they're ashamed of their accent so they won't even try to speak 3) due to their poor lifestyle Parisians are (mostly) dicks and do not represent Frenchies in general.
Don't get fooled by the French people you see on HN (like me) they are a rarity.
Really? Cause that's a pretty dickish thing to say. Also, most people who work/live in Paris are not actually from here, so if you consider Paris to be full of dicks, that would mean most French are too. Just saying.
I had it on the tip of my tongue, but I did not want to sound too offensive; although I dread to say it, it is quite true; however, it's not uncommon to hear people at least trying.
*or however it's written.
Parisians treat everybody badly, it's not specifically directed at foreigners, I'm French and I feel like I'm annoying them too.
Off course I'm generalizing here. If they know you they will treat you humanly. But just try to ask your direction to someone in the street and feel the "love" :-)
I see it slowly changing - I blame this on how good American TV has become now (I'm taking about the series of course.)