Do you use them and if so under what conditions do you prefer them or... dislike them?

I've never been able to prove to myself they make any real difference especially in clear water.  I keep thinking they should help though, especially in deep or dirty water.

I proved to myself years ago no rattles is the way to go  

I had this condition once . The doctor gave me a powder that I had to use 3 times a day. They disapeared in 4 days

Not gonna puke up and repeat info, just gonna tell you my personal experience-

Water clarity, fishing pressure, and depth are the factors that i have found when rattles will help or hurt you with any lure, even topwaters.

I have been out on days where I could catch fish on every cast on a crankbait without rattles but would not touch the same lure basically with rattles.

Same with jigs for me anyway. I also found that a really faint single rattle, will get whacked before no rattle or two regular rattles.

In stained water I like a rattle but not one with an overpowering rattle, I like that one at night.

I had this condition once . The doctor gave me a powder that I had to use 3 times a day. They disapeared in 4 days

;D  Hey Muddy, there is no such thing as magic powders so you might want to double check that just to be sure.

Loud cranks?  Anybody here ever shake a Manns Loudmouth?  Holy geez....