Number 7 is one I don't actually worry about that much when I shoot, but it is usually one of the very first corrections I make as I crop my photos.

A good framer will fix that too, but a lot of people don't think about it. So if the shot is really crooked, the framer can't fix it all the way or too much of the picture will be lost.

A straightener will do the job if its not to out of plumb and you don't lose a lot but hey you can see when you take a shot if its really out of square,should be little problem.

That's true, Ellington, i just think a lot of people (i was a picture framer for five years) don't think about straight lines in photos. About keeping horizon lines level, etc.