Capable people know that they are capable, they have egos, they do not suffer fools gladly, at the same time they are loyal, but they serve a cause not a person. A capable person advances the cause he serves even at personal loss to himself. Only progress matters, presentation is a very secondary consideration.
Cronies on the other hand are also very intelligent but not capable. They specialize in flattery and double talk and are not loyal to any cause/person except themselves. However cronies present themselves as very capable, sincere and loyal. Also cronies never do any work themselves, but spend all their time and energy in taking credit for work done by others. Cronies are very successful in life and live comfortably. They are especially suited to politics.
So how do cronies operate, well they latch on to powerful people and work hard to gain their trust. People in position of power will find themselves quickly surrounded by cronies/sweet-talkers. The capable people will be pushed out by the cronies from the inner circle. The cronies then concentrate on controlling the flow of information and present only information that glorifies them in front their leader. In short cronies start controlling access, both physical and intellectual to their leader. In this way they appear capable and competent and discredit everyone else on some ground or the other. In due course powerful people start delegation authority to the cronies, who use the power to enrich themselves and advance their personal agendas and usually cause damage to the powerful person they have latched on to and whose interests they claim to safeguard.