The different perspectives present in this thread have been fascinating, to say the least!
LonePhilosopher seems to approach sincerity from the aspect of realistic expression, or the apparent lack there-of in modern pop-culture. I agree that the rise of Internet artists like Psy does nothing to further the art of music, but it is a phenomenon I have come to accept because it is an expected product of any liberalized market economy, as opposed to the more traditional economy of yore. People gain the most exposure and success in the public marketplace, not through honest artistic expression, but though what most satisfies the wants of the masses. If people want songs about partying hard and getting wasted, who am I to say that a musician can't give it to them? The trend is sorely rooted in society as a whole, and can only be reversed from within...
On the flip-side, MuppetFace is absolutely right about sincerity as artist integrity. Throughout the worst-of-times and best-of-times, there have always existed examples of those willing to fight against the grain for a common cause. From the Lost Generation of the early 20's, to the Civil Rights movement of the 50's & 60's, Artists have greatly contributed to the foundation of what truly separates man from beast...
Myself? I agree most with Analixus. I can enjoy the latest chart-topper knowing that while the pop stars of the the 50's have been all but forgotten by today's youth, those who change the course of History endure forever. Enjoy music and life while it lasts. Dwelling on the present squanders it, leaving only the uncertainty of the Future in its place...