As frequently as investors might hear about Warren Buffett's time-tested value-investing philosophy, there's a lot that people still don't know about how the Oracle of Omaha evaluates stocks. Most investors don't know that Buffett dislikes companies that need to consistently spend a lot of their revenue on research and development (R&D). Let's take a major pharmaceutical company like Eli Lilly (NYSE: LLY) as an example to explain his thinking.