A recent comment to the "Dumpster Diving for Data" post below mentioned a rumor that a supplier of oligonucleotides was comparing orders against GenBank sequences. For those outside the field, what all that means is that supposedly a company that makes custom small sequences of DNA was looking through a public DNA database, trying to guess what its customers might be up to.
Is that possible? Well, yeah. But is it likely? I have to wonder. Cui bono? I'm not sure how the supplier might benefit - what are they going to do, turn around and sell the information to another company? All that means is that anyone they make the offer to will never order DNA from them again - why risk having that information peddled to someone else? Pretty soon, no one would order from them at all. Actually, this rumor sounds more like something the oligonucleotide firm's rivals might deliberately spread in order to ruin their business.
In the chemical end of things, we expect the major suppliers (Aldrich, Lancaster, Acros, etc.) will keep our orders completely confidential, and I've never heard of a case where they didn't. They fear just the sort of backlash I described - nothing they could make from the order information is worth it.
Now, I have to admit, an off-the-main-road supplier did let slip something to me one time. They were pretty much the only world source for a particular class of compounds, and we needed to get some starting material to take a look at some patented compounds from a competing company (and to appropraite some of their chemical structure, if it fit into what we were working on.) I called this outfit up to ask about the price, and they wanted to know what application we had in mind.
When I told them, frankly, that we were evaluating some compounds from the competition, the fellow on the other end laughed and said, "I think I know who you're talking about - some people in (name of town, name of state.)" That at least let me know that they'd spoken with this company, too, which wasn't particularly valuable information by itself, but more than I would have known otherwise. And even so, it's still a lot more than Aldrich or Maybridge would tell you.