In the first season of Friends, Joey Tribbiani is a charmer - a total ladies man that Ross and Chandler wish they could be more like. He's also got one of the most interesting careers, as a struggling actor, and he's sweet and funny to top it all off. However, as the show continues, there's no denying that Joey just gets worse and worse.
By the end, he's less of a charmer and more of a creep (little wonder he is the only one of the gang who doesn't get a romantic happily ever after!), and he becomes increasingly dumb at the same time. It's a shame, but tenth season Joey is several steps down from pilot episode Joey - here's why.
He Goes From Naive To Stupid
Joey is never the smartest of the group - but he's a whole lot smarter at the start of the show than the end. In the early episodes, Joey isn't necessarily stupid, he's just a little naive. He seems even less intelligent in comparison to characters like Ross, who intentionally patronize him, but he's not completely idiotic. By the end, though, the 'Joey is an idiot' punchline has been taken to ridiculous extremes, and Joey becomes so dumb it's hard to believe that he can tie his own shoes.
He Seems To Abandon His Family
He's not the only one of the Friends to do this, but it seems like the writers got bored of giving any of the Friends parents other than the Gellars, as Joey's massive extended family seems to disappear. In the early seasons, his sisters show up to parties, his grandmother comes over, and viewers meet his (cheating) father and (happily aware) mother. By the end, though, these characters are barely even mentioned. One sister shows up, as part of a single-episode punchline, and then disappears. She was pregnant - surely Joey becoming an uncle should have been a bigger deal?
He Goes From Struggling To Snobby
Joey starts off as a struggling actor, and then launches to fame before crashing back down again. As an arc in itself, this is a great one - but Joey doesn't seem to learn anything from it. He gets the arc without the lesson, which just makes it cheap, and leave him hanging in 'too good for an audition' limbo.
He could have become so much better, but he just ends up back on the show, doing well, but without seemingly learning anything major from the experience.
The Whole Joey/Rachel Storyline
Probably the most polarizing storyline in the entire series is that of Rachel and Joey getting together, and it's easy to see why. Part of Joey's charm was that he was, well, charming - but this storyline took him off in a strange direction. Then, just like with his acting career, he didn't really seem to learn anything from it - and after that, his womanizing ways felt so much worse than they did at the start.
He Actually Grows Down
Everyone else on the show grows up over the years - Phoebe learns that she wants to settle down and get married, Rachel figures out her career, Ross manages to get himself together, Monica and Chandler get married and buy a house... and then there's Joey. While his career does decently, the series writing infantalizes him. As the series continues, he's less of a charming creative type, and more of an overgrown child. He even gets sulky about a stuffed toy being given to a child!
He Turns Into A Caricature
This happens to many of the Friends characters, unfortunately, but none more so than Joey. His 'funny' traits (his naivety and his woman-chasing) go from being part of a well-rounded and lovable character into basically all he is. Despite a few good storylines that show his actual friendships with the gang, these traits are blown up to the extent that they are ridiculous, with him hitting on everything that moves, and being unbelievably dumb at the same time.
The Spin-Off
This isn't technically in Friends, but the spin-off, Joey, was definitely not a hit - and it's easy to see why. The show saw Joey relocating to Hollywood to try and boost his career - where he lives with his sister, Gina, and his nephew, a twenty-year old genius.
The show itself just continues the trend of over-simplifying Joey's character, making him obsessed with food and women, and shockingly dumb.
He Never Paid Chandler Back
This is the kind of thing that sticks in plenty of fans' craws - Joey never seems to pay Chandler back, or really appreciate what his friends have done for him. (And no, an invite to a movie premiere really doesn't count.) Throughout the early seasons, he is mooching money and taking food from Monica's fridge, and it's something every broke twenty-something can relate to. However, when he is doing well toward the end, he's still seen having no idea how to handle money, learning nothing, and treating his friends like a bank - and it just stops being cute when he's earning well and in his thirties.
He Becomes Weirdly Needy
Chandler and Joey are amazingly close - and for most of the series, theirs is a heartwarming relationship. However, in the final seasons, Joey goes from being Chandler's best friend to feeling more like his child. He's sulky, needs Chandler to take care of him and his money, treats Chandler moving across the hall as the end of the world, and then to top it all off, he even needs a room in Chandler and Monica's house! This isn't a friend, this is a needy child, and it doesn't suit Joey at all.
From Charming To Creepy
Finally, one of the biggest problems with Joey is that he takes his dating life from being a bit of a player... to being a bit of a creep. In the early seasons, he dates a lot, but he's upfront about it, and women love to date him. However, later seasons see him placing a wildly inappropriate ad for a roommate, and then choosing one based on how 'hot' she is - and then actually dating her! He starts to cross the line into creepy, and it's just not a cute change.