Hotel thefts in Paris

No, not in 22 years of travel in general and ten visits to Paris. If you look hard enough for any negative reviews or mention of theft for any hotel any where in the world even your own favorite you will find it. People also lose stuff and can be generally careless that is for sure, just ask anyone that works in that industry.
One tip is don't put cash in a suitcase take it with you. (There is no need to carry much cash nowadays anyway as most places you just tap a credit card or phone to pay). Or if you trust putting stuff in the room safe and that you will remember to retrieve it when you check out do that.

I've never run into problems with theft from a European hotel room. I take a couple of very simple precautions and then don't worry about it. There's less reason now to have extra cash, because in most cases you can depend almost entirely on your credit card, but if I have more money than I need for the day, I bury it deep in my suitcase; my tablet computer is worth more, and it's inside the bag as well. I use one of the cheapo TSA locks on my suitcase. That wouldn't be a problem for a thief, but a broken lock would be immediately obvious, and it's unlikely a hotel employee would risk his/her job for the possibility of finding something worthwhile inside my (cheap) suitcase. I stay in comparatively inexpensive hotels, too, so why would anyone anticipate finding good stuff in my suitcase?

Leave the good jewelry and anything of sentimental value at home.

I have not stayed at this hotel but it is one that RS regularly uses for the Paris and Heart of France tours and maybe Best of Paris? One of my early RS guides told me that he NEVER worried about his belongings in an RS hotel because if ANYthing ever went missing from a tour member that hotel would be off the RS list and none of them want that as they like the steady repeat business.

I usually tuck my iPad Mini in the bottom of my suitcase. I don't leave cash lying around and in fact carry a small notepad so I can leave a note saying Thank You to housekeeping. I usually put the note and a Euro on the unmade bed/pillow because if you leave it on the bedside table they usually will not take it.

I am on the team that carries their passport with them during the day in a money belt or stashed in an internal zipper compartment in my purse.

One of my early RS guides told me that he NEVER worried about his belongings in an RS hotel because if ANYthing ever went missing from a tour member that hotel would be off the RS list and none of them want that as they like the steady repeat business

That guide is naive, don't count on that. Just secure anything of value, people can be careless and lose stuff and can say it's theft.

"That guide is naive"

Uh, actually he's not. He's a long-term RS guide and was a RS bus driver staying in the same hotels before that.

I don't worry about thefts in hotels by the staff. I figure they are more interested in keeping their (low-paid, difficult) job as a means of sustaining their family than they are in taking any of my belongings. I don't have anything that would be tempting to anyone anyway. My six-year-old iPad ? Nope. My clothes or pj's? Nope. My couple of pair of earrings? Not worth losing their job over. I don't have any money that I leave in the room. Like Pam, I leave a note that says "Merci" with the housekeeping tip laid on it so it is very clear that that is for them, and they don't have to wonder.

What is the suggested per day tip to leave for housekeeping in Paris?

I have never had a problem in many years of staying in Paris. However I also am careful and either use an in-room safe or carry anything I am really concerned about losing securely on my person or in a small backpack.. Also, usually I am in Rick Steve hotels as they have proven dependable.

We were at a hotel (not Paris) on an RSE tour at which one of the couples' room was robbed while they were out for dinner. Another non-tour room as well. Police were there the next morning after it was discovered. Police suggested it was likely someone checking for unlocked doors (doors did not positively lock well). That hotel is still used and frequently recommended here on the forum, so I don't think RSE investigates or makes judgment on criminal culpability of hotel employees.

Nor is it knowledgeable of how many thieves may be visiting or staying at any given hotel on any given day, presumably.

Never had any theft over 26 trips occurring in a Paris hotel or any hotel at all in Europe, small or big, be it in Sweden, Poland, Germany, France, London, Austria, or Prague. I don't lock the luggage pieces, my spinner or the shoulder sack, ... useless , "they" don't want my stuff anyway.

in nearly 40 years of European travel we have been the victims of room theft once and that was an apartment that was burgled in London and the burglar his the whole apartment building. They got my son's camera (he had arrived earlier than us) but mercifully didn't take his passport.)

Quite easy to leave cash in the room when out and about. Often I leave my summer jack in the hotel, as it obviously too hot when out for the day, either in the city or off on a day trip, in the summer with cash left in the pocket, say 30-40 Euro . Never lost anything in the room in 50 years of traveling there.