I've never had any problems with my Spyderco's, so I don't have any personal experiences to share, but I will say this:
Whenever a company grows beyond a certain point, the owner MUST trust others with their company and their reputation.
Sometimes, these people are trustworthy and care about the company/reputation as much as the owner does. Other times, however, the people who are trusted with the company couldn't care less about the company/reputation. When the latter happens, problems arise.
I'd bet that the people who have had CS problems with Spyderco have dealt with people who are there simply to collect a paycheck, and do not care about the company, the products, or their reputation.
It's simply a problem with growth. You are bound to hire people who will not treat people as well as you want them to.
I don't think that Sal can personally supervise every transaction, or every employee, so there are bound to be a few mishaps.
What matters the most to me is how those mishaps are dealt with.
From what I've seen here, Sal is nothing but a class act. He has always been happy to correct problems that come to him.