For example, some disk- compression tools like Stacker are incompatible with other types of software. So, let's say you know you need a certain type of software, but you need someone to recommend a product. Of course the people who produced it think it's good. They certainly will neglect to tell you about any bugs in their software. Don't ask the salesman what to buy.
Spiffs are basically bribes to get the salesmen to push their products.
Second, just because he works there doesn't mean he knows anything about the products. They will give you an honest evaluation of its good and bad points. This advice is nullified if the friend works for a company that is involved in the software's production or marketing. Reviews in magazines. Respectable magazines like PC World , PC Computing , MacUser , and MacWorld review products objectively every month.