There is a pretty funny article about the dangers of Microstock photography over at Fair Trade Photographer.com.   They do a pretty good job of visually displaying what can happen when you let yourself decide to use inexpensive stock images to represent the people of your company.   This is probably also an excellent time to point out the NXTFoto can usually do a basic portrait of the people at your office on-location in about 1 hour (up to 10 people) and have the images touched up and back to you in a day. Licensing for use on a website for a one year period is also very reasonably price.  Here is a recent image that was one for a real estate agent that need a headshot for business cards and their website. 
We were able to do the photography on-location, and get back edited images and a business card draft in about 24 hours.