Don't know about Ideal world, but my sister is addicted to the jewellery channel. I have bought stuff from their website in the one pound auction section but only if it was something I liked and would wear . Cheaper than the fakes in the market .
The one I avoid is create and craft, especially in the cardmaking run up to christmas( August to October) Their stuff is really nice to work with but ridiculously expensive.
If one of my elderly neighbours passes away before I want her stash, she has been buying from them for years, and like a lot of crafters barely uses any of it.