This is a hard list to populate, simply because many times, what looks like a terrible wrestler is instead a terrible gimmick.
Take Cena, for example. I never saw him in OVW, but from everything I've ever heard, he was really good there. Bring him to the big show, and BAM! Vince does his usual, gives him a couple moves no one else does to distinguish him from the rest of the pack, saddle him with a dumbass gimmick, and stifle any talent and creativity the guy has.
However, there are some wrestlers you can still realize are shit no matter how much perfume Vince sprays them with.
Randy Orton, for example. I don't understand how people can lament John Cena's limited moveset, yet praise Orton, who has the exact same limitation. And the RKO is nothing more than a ripoff of the Diamond Cutter, except Randy always make it look like he botched the move. Cena, at least, has mic skills; I've never heard Orton get through a promo without screwing up at least once.
Another obvious turd is Chris Masters. Yeah, yeah, he's improving. I say how could he not? How many guys did he injure with that stupid Polish hammer move before they made him stop? And how bad do you have to be for them to make you use the Full Nelson as a finisher??? At least they don't let him speak that much...
Even though I feel like a traitor for saying this, the 2007 model Ric Flair is terrible too. I know the man is almost 60. That doesn't excuse anything. I am a big Ric Flair fan, but in my opinion, the time has long since come for Ric to take a managerial role, pass the torch to the younger guys. The man can still tear it up on the mic though, which supports my opinion of making him a manager, the Lou Albano or Bobby Heenan or this generation.
There are many obvious choices for worst wrestler: Khali, Snitsky, Vis, guys that are far too big and/or slow in the ring, and laughable on the mic, that I won't even bother listing them...
The Sandman vexes me. The guy's only good as a brawler; hell, his whole persona is built around the assumption he won't wrestle ya, but he'll fight ya. Usually, with a guy like that, you'll have good mic skills to counterbalance (Stone Cold? The Rock?); but the Sandman doesn't really have that... so what is it people like?
The jury is still out for the moment for me on Batista and Lashley. Both are very limited in-ring, and both need a top talent opponent to put on a good show, but I can't believe Lashley is at his peak at the moment; he's still new to the biz, and he WAS a talented amateur wrestler; Batista, for a perennial enforcer-type big guy, has charisma.
Oh, and for god's sake, could we PLEASE never have to watch another wrestling match Mike Mizanin is participating in? Please? Even as comic relief, this guy sucks...