Extrapolating from two star performers
The most common version. The attributes of two people become the hiring standard, including everything incidental about them. Widening the population and including leavers is the only correction.
Encoding bias
Criteria such as a particular institution, a communication style, or a continuous career history frequently act as proxies for characteristics that must not influence hiring, and they rarely predict selling ability. Every criterion should be defensible as job-related, and this is an area to take proper legal advice on for your jurisdiction rather than to reason about informally.
Mistaking pedigree for fit
A strong record at a larger company in a different motion is evidence of capability in that motion. It is weak evidence about a different deal size, a different buyer, and a different level of support.
Ignoring the selection effect
Your team reflects who you hired before. Attributes that never appeared in your candidate pool cannot show up as predictive, which means the profile can quietly perpetuate a narrow definition of who gets considered.
Judging too early
Assessing a representative on their first quarter measures onboarding, territory, and inherited pipeline at least as much as it measures them.