I only recommend the people that I have worked with that I would want to work with again. Not because of loyalty, but because they are good, and will make me look good for recommending them
The Dunning–Kruger effect is a cognitive bias[2] whereby people with low ability, expertise, or experience regarding a certain type of task or area of knowledge tend to overestimate their ability or knowledge. Some researchers also include in their definition the opposite effect for high performers: their tendency to underestimate their skills.