They only sell those to accredited investors - indeed, the counterparty in the famous lawsuit was a German bank who'd bragged about how they were smart traders playing with the big boys.

Junk bonds are bonds with high credit risk, what’s wrong with selling them to customers who are after high yields?

It's not like junk was a part of the name right?

Didn't they get credit agencies to rank them as premium and not junk though? I think that we know they were junk after the fact.

Junk bonds are just High Yield bonds at a certain rating. GS doesn't set the Price/Yield or the rating.

You have a point, but you may be thinking of the CDOs they and other sold, knowing that they were full of risky mortgages but laundering them through overly-chummy ratings firms.