I use a nylon mesh brewing basket from Republic of Tea for my Rooiboses and it doesn't clog up too badly. A quick rinse in the sink cleans it out pretty well. I'll also use Adagio's paper filter bags, but sometimes they give a papery taste to the tisane, especially with Vanilla Rooibos.
The bagged Rooibos that I have tried, namely the Tazo brand one, tasted awful to me. I definitely prefer the loose, flavored Rooiboses over that bagged one.