Sometimes it goes well, sometimes not. Sometimes it's our fault, sometimes the vendor's. I'm often not the only person involved in the purchasing process, and there are a number of different interests from engineering, operations, and so forth. Likewise on the vendor's side, we may be talking to salespeople, engineers, and so forth.

I'm often the one who has to bear the bad news: "Hey, this thing doesn't work at all."

We do a great job of tracking service and warranty replacements, and the top-ten list is entirely populated by buy-in subsystems.

Certainly "don't trust any salesman" is an over-simplification that may hold pretty well for consumer products, but not so well when a product is complex and technical. But verifying that the vendor is actually capable of what they claim to do, is still considered to be vital.

The vendor isn't always being dishonest. They may believe that we are over-spec'ing something, and that their product really will fit our needs once we are able to lay our hands on it and use it.