I always check the back when I first start and am very careful to have everything as it should be. Soooooo as a result, with my confidence in full-gear I charge ahead and don't do that till I'm well into the quilting. I feel your pain. Been there many times.

I feel your pain! I am currently ripping out deco stitching, which is worse, because what I thought looked good and continued around the quilt...then found out it wasn't evenly spaced....so out it comes....have 2 ft of one side done, 2-1/2 sides to go....and I was so close to being done....

The best way to avoid poor stitches on the back is to make a sandwich and sew a bit on it before starting on your quilt. If stitches aren't to your liking, you can then sew while adjusting your tension until it is right. Then start quilting and check for a while to make sure the stitches are still right. Try to get in the habit of making sure your backing and batting is not under where you are quilting.
I know, so much to remember but it saves time in the long run. I love a large stipple and mostly what I do. I haven't seen a quilt yet that wouldn't look great with stipples.

Always a good idea to check your bottom often...lol. Sorry for you!

I always have a practice piece to try out on first to get my tension set.

Done that more times than I will admit.

OOOOOOOOOOOhhhh Bummer

Triple DITO.......................