MiM has mixed quality as well- sometimes the molds are blown but used anyway.
One bad habit they do have is that they show items available which are not in stock. They take the order but wait for enough of them accumulate before placing the order with the caster for another production run. With some subjects not in popular demand this can take months.
Sadly they are the only source for some kits, you just gotta roll the dice and hope for the best.