Just to clarify for those who might not know, player-created worlds are considered custom content just because they aren't official EA content made by EA employees; but Rflong7's worlds do not contain any extra custom content - unless you count EA content from the Sims 3 Store (and that just gets replaced or will be missing if you don't have it) as custom content.
A few of her worlds have a couple of free EA Store content items or on occasion Premium content items if you own those already. But no third party CC at all. I have just about all of her worlds and I can vouch for that, as long as you download them from the links she posts (not going to guarantee any other places that might have inappropriately uploaded her stuff).
Just wanted to clarify that because I know the whole 'custom content' definition thing can get confusing.