Carpet cleaning is not rocket science, it never has been and never will be. Our job when it comes to stain removal is to search out the very best products that have been specifically designed to deal with a wide range of stains and then apply them correctly and in the right order, and, course, learning how to manage a customers expecations about removing stains that may have been on the carpet for years. It's worth remembering that the minute you tamper with a stain you have in effect taken ownership of it - if it comes out, all fine and dandy, but if it gets worse because you've used the wrong chemical then what? Carpet cleaning is all about mitagting and managing risks - not increasing them by playing Russian Roulette with chemicals that are not designed for the job.
Simon