I've never seen pre-cuts that are 100% straight. If you like pre-cuts there's always a
way to work around it. Starch usually helps. A little fudging here and there too;-)
I would not hesitate to buy pre-cuts if I like the whole collection. Right now I'm
working on a jelly roll sampler using Moda jelly rolls. Well even laser cut, the strips
are not always 100% straight (that's where the fabric has been folded) and some
strips are a little narrower than others. Nothing major.
When I use jelly rolls I usually cut my strips in half (at the fold) so even if you
see a slight "v" it probably won't matter. You have to trim those edges anyway.