Take a good look, some apear to be fine, others apear to have defects and sloppy seals. Also look at the number of pleats. At least with an air filter you can look at what your getting. I have not seen any tests showing how well they filter, but I'd say it's safe to say they're close to other paper filters.
One more thing, if you have a special application with a non-paper filter(some imports) I've seen Fram cheap out and substitute a paper element.