How To Score A Beer?

There does not appear to be a standard, but is there some rule of thumb in the beer tasting world on scoring a beer? I see that homebrew competitions use a 50 point scale with varying values for aroma, appearance, flavor, mouthfeel, and overall. Beer Magazine uses a 100 point scale spread accross Appearance, Aroma, Tast, and Finish, and Ratebeer.com uses a 50 point scale accross aroma, appearance, flavor, pallate, and overall.

Any standard or commonly accepted method in the industry?

Go do a search on the BJCP Exam. It's the ground fundamentals for beer judging. I, and part of my home brew club are studying for the exam to become a judge. It's some seriously in depth literature and there is a lot that is involved. I never would have thought till i started studying.. lol