-Doing unique records.
-FC or high combo a hard map with some mod (that's no one did before) and hold it for long time. For example: neu FL or neu HR or any amazing DT records in hard maps (there are plenty records) .. (old TAG4 records ofc)
-For me I think , that any player with +10k replays watched is totally skilled (or was in someday), that's explain number of views. (or probably as Giorgos said many #1 . (Hold 1 now is much harder so, sure it is a skill!
-Be beast in some mod , or spin!
-FC old maps with strange patterns, and pass with complex mods , DT, HR , or HD as Guruk used to do for example is a skill.
-Accused by cheating..