I had the same problem. I searched and found the following post on the CookingLight site. Maybe try the vinegar again. Good luck.
The pink stuff is really a yeast that grows in damp places. It is also found on shower curtains, shower stalls, etc. Since yeast thrive in an alkaline environment (the soap in showers) using an acid substance will kill it, so using vinegar is the right way to go. Be sure and rinse well, since I don't think vinegary coffee is something you want!
(A microbiologist in my other life)
Julie Keaton
October 2008