I didn't read a lot of posts here, sorry for potential double mentioning.
You suck at Rayman, when...
... Rayman can't hit anything because the Golden Fist is to heavy for him to swing.
... Rayman dies of blood loss against Moskito.
... Rayman dies because he got hypnotized by Mr. Sax' melodies.
... Rayman was caught by Dark Rayman because he ate all the candy he was supposed to walk onto.
... Rayman dies in the Candy Château because of food poisoning.
... you can't find the second Cage in the Woods of Light.
... Rayman beats Razorbeard to eating the 1000th Lum.
... you play so bad that Rayman becomes the main attraction in the Cave of Bad Dreams.
... Rayman needs an oxygen bottle to survive the Whale Bay.
... you fail the Sanctuary of Stone and Fire so often that the plums don't grow back anymore.
... Rayman accidently set off the Fyling Grenade in the Echoing Caves.
... you needed so much time for Rayman 2 that, by the time you've reached the final level, all the Robo-Pirates have already corroded to death.
... you needed so much time for Rayman 2 that, after finishing it, Rayman is deported to the Tomb of the Ancients.
... Rayman gets his hands stolen by a frog.
... Rayman tries to put his savings into the Piggybanks inside the Fairy Council.
... you are stuck at Fairy Council, Part 3, because Rayman ate the Mushrooms.
... Rayman has to throw up because the Vortex-Cutscene was too much for him.
... Razoff has to lend Rayman his rifle to give him at least a small chance.
... you fight against Razoff and have to listen to "Wrecking Ball" to get into the mood.
... Rayman does the Shoe race and realises that he should probably either wash his feet or buy a new pair of shoes once in a while.
... Rayman can't jump the balloons because he got to fat to jump off after eating half the Candy Château.
... Rayman drowns while fighting Céloche.
... the Knaaren ignore Rayman. Why bother? They yearn for brain to eat.
... Rayman accidently swallows a Black Lum after opening his mouth, and has to go all the way back to Clearleaf Forest to see the doctors again.
... the doctors lead Rayman to the shortest shortcut instead because they don't think he can actually finish the longest one.
... Rayman rams his ship into an iceberg before the Fish can sink it.
... Rayman needs a coat on the Summit Beyond the Clouds.
... you need so long to finish the race against Globox that the global warming has caused the Summit Beyond the Clouds to melt away.
... Rayman gets stuck in the Foundry and ends up as a Robo-Pirate.
... Reflux doesn't use the Scepter in order to give you something akin to a chance. According to the RPC-Forum, he doesn't have it anymore anyway.