As bug 55708 and related ones don't see much progress, I'd love to stop this stupid behaviour at least. If something has debug features, the flag belongs to ebuild's IUSE, not into the eclass. Particularly a problem w/ stuff inheriting gnome2.eclass which functions are used by lots of stuff for something completely different than debugging (the database updates in postinst/postrm etc.) Patch attached.
Created attachment 103321 [details, diff] debug.eclass.diff - remove IUSE - use flag-o-matic for C[XX]FLAGS mangling, not the nasty bash substitution
The eclass is dummified now.