Presentation flaws are abundant in web sites, but there has been no study to determine how presentation flaws affect consumers’ perceptions of quality of an on-line store, trust in the store, and ultimately the intention to purchase. The theoretical foundation stems from various relevant streams of literature: trust and credibility, impression formation, and impression management. A laboratory experiment examined three main factors, incompleteness, error, and poor style, and used 160 student subjects in a completely balanced, fully factorial design (2x2x2). It was found that error, incompleteness, and poor style affected consumers’ perceived quality of the web site. Furthermore, it was found that the relationship between the factors and perceived quality was mediated by the perception of the flaws. The perception of flaws rather than the actual flaws influenced users’ perception of quality.