Am I the only one that has difficulty accurately gauging the size of black bears from any sort of distance?

Just yesterday I tagged a bear on a hillside, I thought it was a decent size, but it turned out to be much smaller in reality. Still a legal bear with a decent bit of meat to it. It's also been that I've seen bears thinking they were on the small side that turned out to be much larger once I got closer, or they started moving.