Why do subs sound bloated or slow?

Some people just plain and simple do not like bass no mater what it sounds like . I think many of them chime in their dislike of subs .

Mine are the REL B 2 (pairs) and are far to be bloated and slow ..........

Thanks for the responses so far. In the OP, I wasn't trying to suggest that all subs sound bloated or slow. I was trying to identify some reasons, WHEN subs do sound bloated or slow, WHY that is the case.

Undoubtably, some of those reasons involve the design of the subwoofer itself, as Shadorne indicated. But I have noticed that, even with a well designed sub, seamless integration into a 2 channel system is very challenging. In the OP, I was proposing a theory that explains why sub integration into 2 channel systems so often fails, namely that it tends to result in one of the following scenarios:

1. Good transient response but poor frequency response. Hence "bloated."
2. Good frequency response but poor transient response. Hence "slow."

The reason why the above scenarios are so common, I believe, is because the measures taken to optimize frequency response are often bad for transient response, while the measures taken to optimize transient response are often bad for frequency response.

Has anyone else had this experience during sub setup?

Bryon

If you have good speakers in a 2 channel system a sub is not necessary. Use it for tv.

I have $15,000 speakers in a 2 channel system and the subs make them sound much better. My RELs are in the corners, where REL recomends that they be.