Are you talking Limit or No-Limit?

In SSH, they say that slow-playing flopped quads is absurd (I think I'm remembering their choice or words correctly). Remember that book addresses loose, lower-stakes LIMIT games. I wish I could remember their rationale, but I think I'd tend to agree. If people are going to call you anyways, there's no value in missing out on those flop bets. They're going to stick around and hopefully hit "second best" type hands anyways.

For no-limit, I can definitely see the trapping value of slow-playing flopped quads (and slow-playing in genera). However, it (as with all things poker) is so situational. Depends on type and number of players still in the hand. Depends on whether you are in a ring game or in a SNG/MTT (and at what stage of the tournament, your stack size, opponent's stacke sizes etc.).