Can someone tell when a rogue sneak attacks?

(As if, is sneak attack is a special move anyone could identify?)

Someone, especially one with combat experience or a watchful eye, would be able to tell if your attacks are hitting with a high level of focus and precision over a more hack/slash style, but no, I wouldn't go around saying "he knows how to preform a SNEAK ATTACK."

However, "That bugger fights -dirty-" might be appropriate.

-Cross

However, the dirty comment should more come for the dirty fighting feat (One attack around at the end of turn for another 1d4 damage).

Sneak attack is more a precise hit/shot into a critical area to the victim's body, while he is not aware of the hitter/shooter, thus the victim cannot avoid it.

No?

Precise shots at a specific vulnerable spot of a person's body still seems pretty dirty to me! Dirty fighting is just super-dirty.

All you would know is that the person was excellent at precise, telling blows/shots. You could never identify someone in any sense via sneak attack though.