Do not register in a casino only for the deposit bonus, if that's the only thing you are looking for and do not go with the reviews, you will likely end up in a scam.
I check that the $7 bonus is without need to made deposit, since it's free, I don't see anything wrong to try every sites even though we don't know the reputation. We might ended up playing in scam casinos by asking deposit money to unlock the reward, but as long as we didn't make deposit, we're safe.