If you're looking at dropping $500+ wouldn't you want to know what kind of tension the slide has anyway? As far as I'm concerned rackin the slide a couple times is part of getting a feel while deciding whether to buy it or not.
I always rack the slide several times when looking at a gun for the very reason you stated. Just now I know 100% that is the first thing to do, in conjunction with releasing the mag and doing both a visual and tactile check of the chamber and barrel.