Here are just a few things that might suggest a problem to me, thinking about behaviors I've observed in people who have this problem. Any one of these probably isn't a problem, but if someone is doing a few, I would kind of keep my eyes open. I think these apply to men or women:

1. Seeks mother's opinion about choices he should make on his own or with his partner.
2. Does what his mother tells him.
3. Lives with his mother as an adult.
4. Lets his mother take care of him (food, laundry, pay bills, etc.)
5. Goes out with his mother more often than friends (this may apply to females more)
6. Difficulty dating due to relationship with mother