A DJ can really make or break a wedding reception/party. A guy I worked with was a DJ for a company that I would rather have not hired... so I didn't. All I would hear from this guy every Monday though was how he did an awesome job DJ'd two or three events and really got the parties going. I just didn't trust his boss, so I didn't hire them.
Then, at my wedding (really, its your wife's wedding
), he proceeded to tell me every chance he could that he would've been doing it differently than the DJ that we hired. It really annoyed me and I didn't talk with him much after that. Fast forward a couple of years and guess who was the DJ for my sister-in-law's wedding? Guess who did a horrible job? His boss came to relieve him for a break and guess who was asked to keep doing the DJ services... yup, the boss.
Best thing to do when looking for a DJ is to remember DJs from previous weddings and to get recommendations.