do hotels in Paris give cash discounts?

You can always ask however some may take offence.

I asked this question to a hotel in Switzerland, and they were quite aghast. However, you are correct it is very widespread in Italy.

I asked about a cash discount at the Hotel Leveque once and got a negative response. I said, "I know you have to pay the bank a percentage if I pay by credit card." Apparently they don't see it as an advantage to get cash; maybe they don't like having a bunch of cash to deal with. So I went ahead and paid by credit card. In Italy the hotels often will not accept credit cards ("the machine doesn't work") so cash is your only option.

Thanks, Swan. I had reserved all the hotels with a CC guarantee. None said they couldn't take plastic, they just readily agreed to knock a bit off for cash. I figure the hoteliers preferred to avoid the CC fees.