How does Jaggers show his interest in Drummle

Jagers has a unique interest in criminals. While Pip finds Drummle to be an idiot, Jagers says he is “blotchy, sprawly, sulky....." and adding that he likes “the look of that fellow.” Jaggers talks about Drummle like he is betting on a promising horse in a race. Jaggers likes to think that he is a keen observer of the criminal mind.