I used to use those binders and when I noticed there was bleeding, I changed over to non-PVC flips. I store them in pages with 20 openings and keep the pages in binders purchased at Office Depot. I haven't seen any bleeding since making the change.

The brown binders should definitely be sold with a warning. Maybe some have been fortunate enough to never see bleeding, but that isn't always the case and collectors should be warned of the possibility.