One common misconception about ADHD is that it is a deficit in paying attention (hmm, maybe the name has something to do with that!). It is actually a deficit in regulation of attention--so individuals may have, at different times, difficulty sustaining attention, or shifting attention. Another misconception is that the deficit should be without exception. Everyone, diagnosis or no, is more successful at sustaining attention for high-interest tasks, and shifting away from boring tasks. The more significant skills would be the ability to maintain attention for low-interest tasks, and the ability to shift attention away from high-interest tasks.
