Via Daniel Miessler's blog, I found this humorous story about how he once offended a client:

I was at a client recently who’s (sic) business is providing electricity to a local city. We were trying to figure out what caused a piece of hardware to fail and as I was going over options in my head I asked him, “Hmm…perhaps a power surge?”

Ouch. Clients don't like to be told that their core business may have flaws. But I can see how Daniel got into that situation. I've put my foot in my mouth a few too many times. You see, I was always one of those "shoot from the hip" people -- that's how my old boss used to describe me. I always told it straight, although I did try to use some padding to soften what I said. When I was starting out, I thought people were paying me to tell them what was wrong and how to fix it. It took me a few years to realize that sometimes it's better to get your clients to tell you what's wrong and then propose a solution. Sometimes, you can make that solution address some of the problems they still don't want to talk about!