I have noticed that quite a few artists do not respond to comments to their artwork, not sure why that is but I think it is rude. If someone is kind enough to comment on your work the very least you could do is to say thanks, I understand not wanting to get carried away with a lengthy overdone response, but just "thanks" doesn't seem to much to ask. So for you who this applies to why not give it a try, it really doesn't hurt and might even feel good, who knows. Thanks for reading.