I had one batch of ash arrows from them that weren't sealed well and didn't want to stay straight. Some of them I had to straighten after every shot. Annoying to say the least.
I didn't have that problem with the 2 dozen raw shafts I bought or the first dozen arrows I bought from them, so it's not a problem with ash in general.
You can get by with some very mild bends, provided the tip and fletching ends of the arrow are aligned properly with each other (and the arrows are tuned properly to your bow to begin with)