Well starting with clean chaeto doesn't mean it won't end up with bugs in it, after all it's probably a nicer ecosystem for them to hang out in than the rocks of your aquarium.
Also I love how places like Algae Barn have the disclaimer that they can't guarantee it's completely pest free.... then why do you advertise it as CLEAN chaeto!? Seriously, people are paying a premium to get CLEAN stuff, not to just get chaeto.