I learned a lesson the hard way yesterday: it's not a good idea to wax the static cling-type vinyl sunroof flags!
My story: I've got the UJ flag on my roof. I keep it on for months at a time and it has worked great. Yesterday I decided to try waxing it with some Zaino #2 to give it a glossy shine. Z2 is a fantastic product that works great on most parts of my MINI and I highly recommend it, but, it turns out Z2 acts as a solvent on my flag and picks up some of the colored ink. I don't blame Z2...this is a case of "user error".

The result was not a total disaster, but the white areas of my flag now have a dull gray coating from a combination of the smeared red and blue ink. I am now working on restoring the white by rubbing just the white parts with more Z2 to clean it up.
I do not know if this would happen with other types of vinyl flags or other types of wax, but please don't make the same mistake I did.