Is it really? Or what else could it mean?
It's a nice way of saying "I don't care."
it bores them
1. It is interesting
2. They can't believe you showed/told them whatever you did and feel pressed to give you a response.
3. The person thinks you are holding it upside down, it looks interesting that way.
It's code for I could go for a burger and fries.
I went to charm school and they taught me to say "That's interesting!" instead of "Bullshit!"
Yep!