Sources are drug dealers: some are always(never say always) good, some are good most of the time and some are good so that they can rip you off later(then of course there are those that just scam- but they are not really sources)
they(sources) are people in a relatively high risk business, and like most companies when they take a loss they pass it on to the consumer. Some by raising prices, but others by selective scamming.
That being said, good sources are like good business men-- they either suck up the losses that they have (which invariably happens) so that they can keep their customers(which will pay in the long run) or they get out with apologies(perhaps some refunds- they give up the business)... the bad or mediochre ones scam to make up losses or disappear for a while and are then reborn.... Once they set down the bad path and see how easy it is, few are able to return to straight dealings (though it does happen)
just some random thoughts.