In reply to OllieBrkr:
Incognito doesn't depersonalise your browsing session and "customers also shopped for" is a feature which is controllable by even the most basic e-commerce software. It's not a list of altruistic suggestions to help the customer find products it's a tool to drive profits and shift more profitable items. Amazon's algorithms aren't in the public domain but they will use the same kind of affinity analysis as netflix et al driven by huge amounts of data - as you have discovered it doesn't always give the most appropraite suggestions.
I thought that was the bread and butter of working in e-commerce.