So we're bound to make some wrong assumptions on both sides of the ether, and as behavioral scientists have found over the past few years, boy do we. The evidence has also given researchers a better sense of why we suffer so many digital communication breakdowns (short answer: we're selfish) and what we can do about it (short answer: make some face or phone 

Sometimes it's even difficult to ascertain tone in person.

When all you have is a written word, you can read it as sincere or as snarky and it can take on 2 different meanings.

It's best not to assume. Ask the other person what they meant if it is at all ambiguous.