I used to pitch up and down when Dj'ing but never more than +/- 2, and purely for the dancers. If I am recording a track for home enjoyment, it will always be at 45 rpm exactly.
My good friend Karl Heard was the master of the pitch control. He had no qualms about pitching some tunes up or down to the maximum. Like someone else commented earlier though, it was a shock when you heard them at the manufactured speed. But he could make a winner out of a duffer, a great Dj.
Also, the people who have turntables with no pitch control, and who think they are purists. You better get your equipment checked regularly, because I have owned decks that have been miles off pitch when checked by an audio technician. One in particular I had for years, and all my recordings are ruined as the speed is too fast. You get used to your own turntable, so you don't notice any subtle changes. Some electrical components can deteriorate over the years, as can belts. I had to have some components renewed in my Sound Burger, and that had never been used.
With a Technics 1200 or similar, you can see that the turntable is spinning at the true speed, with the strobe. Peace of mind.