you have to take in account the quality of life many snake charmers themselves are forced to deal with. Being Indian by descent, and having visited many times, I have seen some snake charmers with animals that appeared to be in good condition, but like you said, they are likely freshly caught animals. The thing you have to consider is that for these people, "snake charming" is the only means by which they can put food on their table, and they barely are able to do that. The animals are nothing more than a means to do so. It's unreasonable to expect someone to care about taking care of an animal when they can barely do so for themselves and their families.
It's extremely easy for us here to cry animal abuse, animal exploitation, etc. when we are in the comfort of our upper-middle class lifestyles (even lower class here in the U.S. is extreme upper class to these people). I'd wager every cent I have that ANYONE would do the exact same things if they had to in order to provide for themselves and their families, even if the animals' welfare was at stake. Why would anyone be concerned about the welfare of a snake when their life is essentially hanging on a thread? Besides, it's not like these guys can go down to Petco and pick up some rats for their charges...some keep 'em till they die and collect new ones, others do their best to care for their charges.
While as a snake lover and animal lover in general, it pains me to see animals in these conditions, I also have to think about the people themselves, and try and look at it from their point of view. To them, the few rupees they may be able to collect a day from "charming" a snake with it's mouth sewn shut is the only thing that prevents themselves and their families from starving to death.
