Same as Daniel.

Um, it's a weird combination with absolutely no consistency or logic applied to it, you are all subject to my whims

Generally when I liked/nodded my head in agreement or something that was stated resonated with me.

i click the smiley button when I like something or it's a response directly to me. i don't smile irl. :p

I only smile if someone says something interesting or funny. Makes it more special

When it directly interacts with my content, read receipt. When it doesn't, it's because I liked it

Nope, I use the smile when its made me smile or giggle. Just assume I read all answers because unless its an essay - they're easy to read.

If it's a reply to my question it means i read it and didn't find the answer completly lame or dumb

I usually smile it if I like the answer or the person