Is this bad?

Probably not - people are full of contradictions and don't always follow through on their plans. Just make sure it's true for the character and you should be fine.

Contradictions are great. People are complex and they don't always do what's expected. It leads to conflicts (both internal and external), and mistakes, etc. However, unlike in real life where things might not be explained or understood, novels are different. You can't let your characters do something with no rhyme and reason and contradict the character's true self without elaborate on that somehow.

Say, if your character is a kind man but understand some circumstances he decides to kill -- that's interesting, but if you don't leave the readers clues or if that action comes out of nowhere and feels off, then you're cheating the readers.

I have a question, though: Are your characters doing these things because that's what they do, or are you (the writer) MAKING them do certain things? The former leads to real characters, and the latter makes puppets. If you want to write stories that parallel real life, you should try to have real characters, and not puppets.

Someone famous--and of course, I've forgotten who--pointed out that there often isn't an internal logic to real life.

However, just like writing dialogue the way people actually speak would be obnoxious to read, writing life the way it happens is likely to be a disappointing experience for the reader. People accept real life because hey, it's what we've got to work with, and you don't have many other options. But there are TONS of other books, so they don't have to stand for yours if it's as inconsistent and tortured and meandering as reality.

People act very very stupid in real life, but if someone acts stupid in a book, people read it and go "Dude, nobody would be THAT stupid." Well, sure they would, but in a book it's really annoying.

Real life never wraps up the loose ends, it really usually IS the most likely suspect, and sometimes you never do find out whodunnit. This sort of behavior would aggravate the living hell out of readers, though.

So...err...yes, for my money, taken too far, it can be bad.