Never buy something on a contract. Why? Because if they cannot sell the service or item without a contract, then it means the item or service is junk.
If there is nothing wrong with the service or item, then they would have no problem selling it each month, without a contract. It's so bad they have to force people to buy it, using a contract.
For example, the bug man. The bug man does exactly what we have already been doing. We have just as many bugs before he started he's so called service. We cannot get rid of the bug man because of the contract. Now the bug man has become a pest.
Another example is phone companies. They know that after the first month everyone is going to cancel and never buy it again. What do they do, 'contract'.
Staying away from this scam is easy. If they require a contract, then never buy it. A contract means the service or item is junk. It's something they cannot sell unless they trick people into buying it beyond the first time.