rosco - spot on what you said - in my oppinion its fine to behave like you described when teaching someone something- its often part of the learning process.
What makes me sad and what i hope i never do (when ive learnt anything someone other than children want to know!) is crush anybodys enthusiasm. Somebody might be stupid, naive, careless, lazy, undedicated, whatever and sometimes its best that is dealt with, but enthusiasm should always be recognised as the good and precious quality that it is. There are far too many cheerless cynics in this world without adding to it!
For the record i have found ALL you experts lovely and patient and informative, but anyone tired of answering beginners questions should maybe ignore our posts and let someone else take up the task - everyones a winner!:)