Consider microstock giant iStockphoto's perception of scientists:
What is singularly disturbing about this result is that iStockphoto's top search results aren't determined by the company. Like any good search engine, iStockphoto's ranking algorithm is a dynamic, organic process driven by statistics drawn from past interest in the content. The Scientist-as-Mad-Scientist, and the lab-coat-and-blue-liquid cliché, are driven by image buyers.
Thus, these are images that conform to preconceptions of how society wants scientists to look. Stock agencies are selling society back its own stereotype, and the merry-go-round spins ever onward.
Now go do yourself a favor and have a look at real scientists.