You have probably been affected many times already without really noticing it... as a matter of fact, bumpmaps are hardly used for details (most of the time), people typically only use them to "roughen" surfaces. In this case it hardly matters if the template is correct, and that's why people won't see the mistakes created by either the Poser bug or stuff like turning .bum files directly into grey .jpg's or .tif's - as long as the surface still looks rough, everything is fine for them. Every now and then when it does matter - like a scar on the body with moving lights - people just curse Poser for not supporting "real" bump mapping. If you have problems with a bump not looking as expected, then it will almost certainly suffer from the inverted channel. I tried to find an automated fix but gave up - this bug is really cursed. To repeat the "Escher" metaphor: telling a valid .bum file from a damaged one is similar to tell a real drawing (that might exist) from an Escher picture - you need to "understand" what it "really is" in order to judge it...