I've used them as side table toppers. I have a pretty red, white and blue quilt that I had under a few plants on an end table i no longer have, and I think table runners or place mats / blocks used as "doilies" or coasters are fine, but I never would have thought to use a quilt as a table cloth.
What gets me is tree skirts. There are some beautiful tree skirts out there that get covered with presents. Not that presents are bad, but you don't get to see the prettiness of the skirt!
I've also seen place mats, table covers, and potholders done in cross stitch - to that I say no way! All mine is hanging on walls, nothing that takes that much time is going to risk spaghetti sauce or blueberries, because it really does slightly dye fabric and floss.