I separate skiers into the following categories. This is my take on ability and versatility.
Green level Start up skiers
Blue level or intermediates Recreational skiers, some
instructors
Advanced Blue Instructors, recreational skiers
Advanced skiers who can ski Black terrain Most Instructors,
recreational skiers
Black Level skiers Instructors, trainers,
examiners, ski racers
Experts Few instructors, (some
demo team members) all
mountain competitors, ski
racers below seventy points
FIS.
Experts with elite racing ability Racers, all mountain, national
team, college
racers, top ten NCAA only.
Examples of skiers that would fill in the categories:
Experts, and all mountain with racing ability, Tommy Moe, Jeremy Nobus, Chris Davenport
Experts:
Eric DesLauriers, Dan Egan, Shane McConkey. Doug Combs
Black Level:
Most instructors who are examiners, but even within this group there are some who don't handle all mountain Black terrain very well.
Advanced who ski Black: Most ski instructors and recreational skiers
Expert skiers can control speed on icy black terrain, cutting round slalom turns, leaving two tracks. This is a high level skill and requires strength, training and talent. This is beyond but only a handful, few demo team members are able to ski these turns. These are fair, realistic categories, without any embellishment of abilities.