My work computer is spotless. My personal conference (and work appropriate - security wouldn't find anything unprofessional or untoward on it) laptop is the one with some stickers that are technologies that I want to put on there. My personal computer at home is desktop... so no stickers there.

Even crossing company culture borders could be problematic if one is a consultant or sales engineer or professional services... This is one of those "in the wrong environment, something could scupper a deal - and you don't want that to be pinned on you."