Vikki. Your ability to teach is not in question. What is in question is some folks ability to learn. You cannot make a silk purse out of a sows ear. Even you must admit that there are some people who just have not the ability to sing in tune.
There was a TV program called so you think you can sing. It featured tone deaf no hopers. They were put to a top vocal coach and a course in singing. The point was to compare before and after performances to see who had made the best progress. The after results were predictable, tone deaf no hopers who still could not hold down a tune and probably never would. A complete waste of time and money.
My advice when choosing a hobby pick something that you are reasonably good at and enjoy doing. Something you can progress at. Otherways is a complete waste of time.
Derek Re "You are what you are if you're good at singing classic rock(which is debatable depending on my ears)"
I took the opportunity of listening to some of your Soundclick offerings. I will not comment further except to say you may want to book a few lessons with Vikki as she says she can work miracles with tone deaf no hopers. You may also want to get your ears checked out.

http://www.soundclick.com/bands/songInfo.cfm?bandID=687727&songID=5238055