yes I can tell by a picture, I've been judging plants for my fellow growers in this area for 2 years as well. so I have a lot more experience than just with my own 12 plants.
just because you can't seem to do it after 6 or 7 years doesn't mean I can't. we are different people with different capabilities. no offense.
FDD posted a thread about this a long time ago, it's in the harvesting and curing section, called harvest time, a tuturial. I suggest you read it.
and I am not against using scopes, I use one myself, but I find looking at the whole plant to be just as useful as having a scope.