The first time I started having any real problems with the dub was… the rap opening, for one. It pissed me off more than anything that 4Kids lied about how they were going to treat the series, and I think they owe it to the fans to just say "Okay, we're going to re-do the music and we'll have edited DVDs." The fan base is still pissed, but if they're honest about it, it's not going to be like "Oh yeah, near-uncut dub with original music and good voices SUCKA PUNCH." To be fair though, there's a certain level of accuracy in the first three episodes that doesn't carry over to the rest of the series, so I'm guessing that they were going to keep to their word, but someone screwed it up at the last minute. But it's best not to dwell.
Beyond that, when they started splicing episodes in the Kuro arc and also when they started giving the characters stupid voices, beginning with Usopp. Going further... The stupid "chakram will turn on you" thing, Kuina's death being censored, Sanji's voice, Bellemere's death being censored, more snip snip and ESPECIALLY splicing all of the episodes in Arlong so they could GET TO DA CHOPPA, Fantastic Voyage! was terrible, no Little Garden, playing down Hiriluk's death, the upside-down hook thing, and just destroying any impact that the conclusion to Alabaster should have had.
The stupid hammer gun, name changing, lollipop, etc. crap doesn't matter to me. What they did to the show goes far beyond "OMGEESH GUYSH THEY CHANGED HIS NAME BY ONE LETTER."