Here are some tell-tale signs:

Headshot pics only or generally pics that obscure her body in some way.

List best feature as "my smile" or "my eyes" etc. A attractive girl who is body confident will always put her arse tits or legs as best feature.

Girls who list their personal qualities as "kind" "loving" "genuine" and other fluffy bunny type words, attractive confident women tend to use harder more aggressive terms like "sassy" "driven" "ambitions" etc, they arn't trying to sell themselves on their personality because they know they don't have to.

They say "my friends say I am ....", an attractive girl just says "I am ..."

There is an undercurrent of confidence in the way an attractive girl presents herself and in her communication. You get attuned to it after a while.