Do scales and no legs always = snake?

No. There are a number of lizards with no legs (represented in North America by some members of the families Anguidae and Anniellidae, glass lizards and legless lizards, respectively), which are often mistaken for snakes. This confusion sometimes results in the stomping of these harmless lizards by highly sophisticated folks who think that "the only good snake is a dead snake" in their crusade to rid the land of the evil serpents, and other people simply miss an opportunity to recognize and appreciate a beautiful and unique lizard.

Here are a couple glass lizards, followed by some neat snakes I've recently found:


Subadult Eastern Glass Lizard (Ophisaurus ventralis)
In this photo, one can see the external ear opening just behind the jaw, which is one of the visible characteristics that distinguish a lizard from a snake.



Adult Eastern Glass Lizard



A new form of this species for me - "Yellow" Eastern Rat Snake (Scotophis alleghaniensis)



North Florida Black Swamp Snake (Seminatrix pygaea pygaea) almost ready to shed (notice the cloudy eyes)



Black Swamp Snake - with brightly-colored belly showing



A new species for me - Florida Green Water Snake (Nerodia floridana)