I haven't had too many issues with sizing, however I have had a few disappointments when it comes to quality. It's a little bit of a stab in the dark but I figure if it's only risking $10 it's not such a big deal. If it's REALLY bad, I'll cut it up and use the fabric to make something I'll actually wear.
Or, more realistically, stash it in my fabric bag and never look at it again.....
I buy nearly all my clothes online, as I really dislike clothes shopping! When I use a site for the first time it might take a few goes to work out what size fits me but then after that it's usually ok.
I've only sent one item back for being the wrong colour and that was my husband's fault - the dress was available in a dark blue or an orange, I had wanted the orange but he persuaded me to get the blue... when it arrived I just knew I would never wear it so sent it back and exchanged it for the orange, which I love and wear a LOT!
Most online sites here have free returns so it's no bother to send stuff back if it doesn't fit. I would far rather do that than have to spend a day at the shops!
I've actually never considered buying clothes online. I like to see and feel the fabric and try them on. Waiting for them in the mail and finding they are not right, then having to send them back and wait again sounds like a pain in the rear.
I used to do that a lot earlier. It was so much easier where I lived before, they would send somebody to pick it up if I need to return it. And If I want another size, the person would bring another size while coming to pick up the earlier.