Pretty much everything, same as with other denominations. They're mostly all 501(c)(3); they all want your tithes; they celebrate pagan holidays like Christmas, Easter and Halloween; they're respecters of persons (don't you DARE question the pastor!) and they flock to all sorts of wicked, unbiblical teachers such as Kenneth Copeland, Joyce Meyer, Benny Hinn, et al; they don't sanctify themselves from the world; really, too much to mention everything.
The topics I just mentioned are all topics Chris has written articles on. I would really encourage you to go over to the website and just start reading.
With all the questions you're asking about what's wrong with the Pentecostals, though, I'm really starting to wonder if you really do want to sanctify yourself from them. Are you really looking for the truth or are you looking for an excuse?
In your original post, you asked about how to 'undo' all the false doctrine you've been taught over the years. The answer to that is to simply start reading the Bible for yourself. Chris has done an excellent job of explaining a lot of things, but reading his articles and listening to his teachings are no substitute for just getting into the Word for yourself and studying.
2 Timothy 2:15 Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.
Acts 17:10 And the brethren immediately sent away Paul and Silas by night unto Berea: who coming thither went into the synagogue of the Jews. 11 These were more noble than those in Thessalonica, in that they received the word with all readiness of mind, and searched the scriptures daily, whether those things were so.