I don't really like Watto, but I will say he and Palpatine are the only characters in the film who's motivations and characteristics make some degree of sense. Other the fact that as slaves go, Shmi seems to not really do anything for him Anakin seems to have way more time and materials than is credible, everything else does fit. He's a sleazy junk trader who likes to bet and thinks he can make some money off some naive off-worlders.

Its simple not particularly meaningful, but compared to most of the other characters its down right Shakespearean.