I didn't read through all 43 preceding pages, but if you were really interested in finding out if they boosted, why not just check the achievement page?
Statistics page lists # of quests completed for individual toons. Obviously a insta-90 will have less than MOST toons, depending on how you leveled. From there you could continue on to BG and Dungeons.
With all that said, personally I don't care how someone got to 90.