I heard a rumor that the faucets purchased at plumbing supply stores are superior to faucets purchased at big box home improvement retailers, such as Home Depot. Just ask any plumber about this, and they'll probably tell you it's true.
Here's how the story goes: a homeowner contacts a plumber to have a new faucet installed, which they've already picked out - a Delta Addison faucet they saw at Home Depot's web site for $349. The plumber will install the faucet, but won't give any type of warranty on the faucet, because it's an inferior product compared to the faucet the plumber would get from their plumbing supply store. If the plumber provides the faucet, it will cost a lot more money - the list price at Delta's web site for the Addison faucet is $514.45.
The plumber goes on to explain that the faucets provided by a plumbing supply store are superior; while they may look identical, the 'guts' of the same faucet are of a higher quality when they come from the plumbing supply store, and less prone to failure. For this reason, the plumber will only warrant the faucet that comes from the plumbing supply store, for a much higher price.
Reality Check
I've heard this repeated so many times, from so many sources, that I decided to do a little calling around. I called and spoke with reps from Kohler, Delta, Moen, American Standard, and Price Pfister. They all flat out denied this claim. They say there is no difference in faucets that go to different retailers. They're all the same.
American Standard said that the drain assemblies they ship with some of their lav faucets that go to plumbing supply stores will be made of metal, while the faucets that go to big box stores will be made of plastic.
I suppose it's possible that all of the manufacturers were lying to me, or that the reps I spoke with don't actually know what their talking about... but how likely would that be?
In the plumber's defense