Not exactly, but the stars really have to align for a beer to score a perfect 50, including several factors that aren't even within the entrant's or judge's control (such as if it was mishandled during shipping, stored improperly prior to the competition, delivered to the judges sloppily, etc.). From the BJCP Study Guide:
"In general, the best beers at a competition should be assigned scores in the 40+ range, with real evaluations of the beer identifying some characteristics of the beer that make it non-perfect. A beer receiving a perfect score of 50 must indeed be perfect; it must have absolutely no flaws, exemplify the style as well as or better than the best commercial examples, be perfectly brewery-fresh, and be wellhandled and presented. These conditions might not all be under the brewers control, so achieving a perfect beer at the point of presentation to judges is extremely rare."