I always test unless I'm certain something will work--even then, I usually test. ("I am only an egg.")

I almost always reformat code if I touch it at all--ever read Stranger in a Strange Land? My most quoted line from that book is Jubal Harshaw's "After an editor pees in it, he likes the flavor better" (or words to that effect).

I sometimes try out code--usually fragments. (I don't have an SiaSL quote to go with this one--sorry.)