A good teacher is made up of so many things. Age and experience are just two aspects, and you can't judge a teacher based on age and/or experience alone. Moreover, relationship between teacher and student requires a special chemistry and rapport, and a good teacher for one person may not be good for another.
There is really no answer to this as there are so many unknown variables (past qualifications and musical career, current work, character, etc.).
To eliza9237:
RE: 好多中外著名既演奏家都唔一定教得好
Please quote ONE example. And please don't say Beethoven.
I am sorry but I don't believe in that. It is a common "lie" created by inadequate music teachers that famously good musicians are not good teachers. Any good musicians will tell you that a student should stay open-minded and listen to other good musicians. If you say 好多, then please furnish us with some examples and reasons.
2007-01-24 20:07:22 補充:
Yikes... a clear advertisement blended with an unhealthy load of cheesy sentiments. Not actually answering the question. The correct email reads
[email protected].