Deal breakers are few and far between for me...but there are some... Slip joint folders with either too weak or too strong of a back-spring. Knives that are uncomfortable in my grip. Swiss Army Knives or multi-tools without scissors. Knives made in countries that are working against the United States. Knives that have tacky or garish logos or text on them. Knives with names that I would be embarrassed to utter. Knives made by unethical or shady people or businesses. "Sharpened pry bars".