What they definitely are best at is significantly quieting the noise of the hookah. As far as smoother smoke, bigger clouds, etc. etc. I can't say one way or the other. IMO it does make the smoke slightly less harsh. However it also restricts the pull a little bit so you have to work harder for your smoke. Not much just a little but it is noticeable. Worth $10? Maybe. I like mine but can only use the small one as the large size is too big for my SSC Sub-zero. SSC versions are sold singly for about 1/2 the price. Or as was mentioned before the Home made hookah stuff section of the forums has tons of ways to make your own.
My video review: