One of the most important things to keep in mind when deciphering between unwanted cynicism and useful criticism is being able to judo the feedback - Acknowledge the cynics comment, build on the idea and essentially further the feedback with excitement. I've always found to interpret with an open mind retort with a methodical approach. The main problem with us designers is the batch of self-made koolaid that we consume daily. A fresh pair of eyes should always be welcomed. As a designer, I always have a "go-to feedback crew" who will always offer unbiased opinions ultimately setting up a better conversation with the cynics.