I think the best way to overcome this is to not leave valuables in the room. Whatever you bring on holiday, keep on yourself. That's what I do anyway, and I've not had a problem with never needing to use the safes. Because whether it's in a safe or not, hotel staff might go riffling through. I suppose a safe is better than bedside table draw though obviously if you have to leave something because at least then maybe the housekeepers can't get their hands on stuff.