The incorruptibles are pretty crazy. We don't have any current scientific explanation, really, besides sapofication (which doesn't really hold up). You usually get that kind of thing from bog preservances and things of the sort, not the type of caskets the saints and whatnot were buried in. I believe if there is indeed a God, he's making images out of these people --- ideas incarnate. Some people may not find it enough to believe in God and say it's scientific (and it may be true the Church found a way to specially embalm their treasured members), and others find this as another way to reassert their faith in God. Whatever works for 'em.