For a change - Sales and Marketing are right Never EVER hang dirty laundry in public
Bullcrap. Ask marketing to provide proof (not anecdotes - real proof) on the number of people who have switched away from the product because of the bug reports. After all - marketing is supposed to be about numbers, how action x produced an increase/decrease in uptake, etc.
People know all software has bugs. Hasn't stopped Microsoft, Apple, IBM, Amazon, from doing business. If marketing doesn't know how to "feature" this openness - by emphasizing the responsiveness to users (not that it's open per se), then they're idiots.