It's easy to assume that a someone needing user support is not using the application correctly. What if there really is a bug?
We've all seen the acronyms used by support techs: ID-10-T errors, PICNIC, PEBKAC, and so on. On the one hand, they're pretty mean-spirited (but kinda funny). On the other hand, support techs can legitimately be exasperated when rude, frustrated users scream at them to solve problems that aren't their fault. Yes, some support techs really do have to walk users through the most basic of operations like making sure the computer and monitor are plugged in and powered on. On the OTHER other hand, it is the job of support techs to bridge that knowledge gap.
As consultants, we are often called upon to support our own or someone else's software. We have to be the opposite of that acronymic stereotype. Users aren't idiots; they're experts in something we are not proficient in and vice versa.
Once in a while, we are on the receiving end of customer support, and these experiences can be real eye-openers. I remember one instance where we discovered an undocumented limitation of a mature third-party application.