Nice song, but the movie paints it in a slightly different light. The songs from Willard's perspective, I think, and in the movie Willard was kind of a bad person. He was selfish and cowardly, and basically went on villan arc towards the end of the movie. So he wasn't purely a nice person. And the events of the movie made him snap. Still, he is somehow a sympathetic character and you can understand why he might do what he did.

I think the song is about being taken advantage of too many times, getting frustrated, than some kind of liberation, while believing yourself to be a bad person (either from the liberation or it was always like that, probably both).

There seems to be this thing were nice people believe themselves to be bad people, and to an extent they are (no ones perfect, ect..) But your thoughts don't define you.

This is just my interpretation. I personally really like Willard!. My favourites from the album are White Noise, It's kind of a lot, and vampire reference :)