Absolutely enormous amounts of these scams on anibis. I encountered at least 5 a month. They're mostly quite obvious - if the rent is ridiculously low, it's a scam. Don't even bother emailing. There was one where the rent was cheap, but feasible. The email that followed was not immediately identifiable as spam (these types of email normally are) and it wasn't until he demanded I pay 200CHF odd to have the key delivered that I went "Oh, ok - you must think I was born yesterday". Sadly, having just experienced how incredibly difficult it is to find a flat and having felt so helpless and desperate, I can see how someone more naive might fall for the better ones. I'm extremely suspicious of everyone which helps.

If you're wondering if it's a scam or not, it probably is.