Striking the balance between quality and a cheap hotel is a fine line. Start by going with names you know. If you have not heard of a hotel and the deal is low, chances are it's a dive. By going to popular hotel chain websites, you can see some deals they offer for internet-only booking.
Another way to get a cheap hotel is by going to discount hotel specialist websites such as hotels.com. These websites claim to be able to get the lowest prices on your hotel room or they guarantee you a refund. That is reliability AND safety, and worth checking out.