Re: has anyone had a canvas that has turned out to be the devils spawn to paint on?
As a student, I buy the cheapest canvases possible for my classes. I know they're going to suck anyway. I have real canvas and make my own stretchers from 2x4s for my real work, but the classwork gets expensive and they are not keepers.
I buy the cheapest possible crap canvas, preferably in multi-packs, from Hobby Lobby or Micheal's, using the 40% off coupon they generously supply online. You don't even have to print it if you have a smartphone, just show it to them on your phone when you check out. Then I apply 2-3 more layers of gesso, sanding in between, and this usually smooths out even the cheapest crappiest canvas enough to smack some paint on in class.
I did have one canvas that was a nightmare during my first class, but it was really my own fault. I didn't cut the stretcher bars properly, and ended up using store bought ones until I could cut more. Then I unstapled the canvas from the store bought stretchers and transferred it to my corrected stretchers after it was gessoed, so my instructor wouldn't yell at me (she had a thing about making your own canvases from scratch). Of course it wasn't an exact fit, so there were lines where the original stretchers were, and the painting was cursed from that point forward. It warped, the canvas is becoming unraveled at the edges, and it's not worth painting over.
I'm really glad my other instructors didn't care about store-bought canvases.
Follow your bliss!