I have seen most of the host give you cash back if you don't like their service in first 30 or 45 days. Do you think the Host will try to make the experience better for the users to sustain them or stay honest and provide the same spec when a user signed up?
If they are serious about giving the money back, there is a good chance that they will try to avoid it. ie, give good service at least during that period.
If it is just an advertisement and they have no intention to refund you, then you are on your own. I don't want to blame them all. Some of them do honest business and try interesting methods to gain new customers. If that is the case, you just got lucky.
Some of them are genuine. But make sure they will refund. A lot of big names offer refund as a tool to get new users. It works too. In the end, all of it comes to your judgement of the other party.
One month cost won't be much high. If you are going with a shared hosting that will be $5 maximum. If the amount is too much, be careful what you commit.