Good and bad mind viruses?

You're just substituting the word 'thought' for the word 'virus'. A virus-proper being a physical (although tiny) entity. A computer virus being an electronically-coded entity. A thought being a metaphysical or bioelectronic entity.

Different things, already given their own definitions.

NB: Similarity of 'mind viruses' to an academic/intellectual form of sociocultural memetics. http://en.wikipedia.org/wiki/Meme