It's not rubbish walker101 - You are in the minority. You're speaking from your own experience. I'm speaking from many many peoples experiences. Not only that but there is also scientific evidence to back up the fact that most are not worth their money. Particularly when you can get some mature media/filter gunk that does the job and is guaranteed aswell as being relatively cheap/free.
Trabetta - I do agree with Jonty. In my experience, having seen white clouds and taking into account their activity levels/size I personally wouldn't put them in anything shorter than 2ft. Bioload wise they're fine for 5 gal tanks, I believe this may be all the sites you're looking at are taking into account. What sites are you using out of interest?
Just a note by the way, WCMM should really be kept in groups of 5 or more to give them the ability to shoal and feel comfortable.