Do external factors ever matter (e.g. the building is condemned and you know it will be torn down by x date, the building's in terrible shape and likely won't last much longer, most of it's undamaged, but part of it already suffers from water damage and/or mold, it's in an area vulnerable to taggers and vandals, you know it's highly unlikely anyone will ever come back to it, etc.) or should urban explorers always stick to the creed "take only photographs and nothing else"?
I'm curious because I've seen a whole range of responses from "never take anything" to "free stuff!" and I wonder what people here think.