If you don't sign a contract, you don't officially rent there. I don't think you'd be covered by any kinds of rights, but I can't be certain. In my opinion, if they want the money before you've even actually moved in, there's a high likelihood that it's a scam. If they'll let you move in and then pay, it's more likely that they're just trying to avoid paying taxes on the rent.

I've tried non-contract renting and it wasn't worth it. The guy didn't scam me, but what he was doing was illegal. He didn't have permission to rent out the part of the property that I was staying in, and I paid the rent in cast, so he wasn't paying taxes on it. This meant that while I wouldn't be in immediate legal trouble if he got caught doing it, I would be without a place to live because his own lease would be terminated (he was renting the house himself).

When I originally agreed, it was because I was in desperate need of a place to stay in a new city where I was starting college, and that was the only option available on short notice. However, it didn't take long before the aforementioned concern started to weigh on my mind. The fact that I could potentially end up homeless at any moment became a real problem. Fortunately I had been on a waiting list for a college dorm for a long while and ended up getting a place there before anything happened.

I believe that if you get stiffed by your landlord and have no contract, you can still try to open a case against them, but you're unlikely to get very much out of it if you have no proof that you paid them. If you're in the problematic situation of needing somewhere to stay and this is your only option, you should at least insist on a receipt for rent paid. Make it a last resort, though.