There is something suspicious in itself about ordering laboratory glassware. When clandestine chemists buy, they use shell buyers, dodgy distributors, false letterhead, and/or squirrel purchases across many distributors.
Clandestine chemists would prefer not to send their glassware to 15 Methlab Lane, certainly. But most of the clever paranoid tactics are for the acquisition of chemicals, which the DEA has a very tight grip on. In some cases, precursors of precursors. A chemical supplier can pretty easily divine illegal applications from the order combination. Glassware suppliers cannot. And I'm a laboratory glassware seller, so I can say that with some certainty.