Cleaners don't seem very reliable or honest... we got rid of one for being lazy and had to prosecute 3 (2 of them at the same time - brothers) for theft where I work in the last few months.
Nice generalisation.
Unfortunately a lot of people think cleaning is the "bottom of the barrel" kind of job, when in fact it requires a lot of common sense, dedication and character to perform it well. What that means is that everybody thinks they can do it, when from experience, a lot of people just can't hack it as a cleaner.
It's easy to be judgemental when you're going to work in your suit, or sitting at your desk in your office, or standing behind a till, but if you took the time to realise the kind of position being a cleaner puts you in, I don't think you'd be so quick to judge.
I'm no thief. If I find a wallet with ID in it, I'll hand it in. If I were to find a mobile phone, I'd do the same. Yes, there are people who would take things that don't belong to them (specifically knowing of a way to return it to it's owner) - but I wouldn't go so far to say that "Cleaners don't seem very reliable or honest" just as I wouldn't say that "People who work in an office are stuckup morons".