Originally Posted by
TerryK
Seatmap is useful to view available seats, nothing else.@:-)
It is
not a good indicator of load. Passengers on low fare classes cannot reserve seats, as well as tour groups; many Asian passengers don't know there is such a thing as pre-reserved seating.

A nearly full flight can have nearly empty seatmap.
That has also been my experience. I remember a few years ago (when I started to book flights online), I booked a flight with high seat availability thinking that it would allow me to spread out. I was in for a nasty surprise once I actually boarded.