"And therefore, since I cannot prove a lover
To entertain these fair well-spoken days,
I am determined to prove a villain
And hate the idle pleasures of these days."
(I, i) (Shakespeare)
There is no doubt from the very beginning of the play that Richard is very evil, he is open about it, expressing his temperament, making it clear from the start.
"Richard III is a born villain, pushed to the forefront by the evil of others but, at bottom, a biological and psychological freak of nature who has played an active, conscious part in his evolution into the role of arch-villain."
Richard is really bad, in fact, he is evil, he is driven by a lust for power, an ambition that knows no boundaries. His desire to be king propels him to do the most despicable things, and what makes him so evil and treacherous is that he is capable of committing the most evil acts with a smile on his face, masking his true intentions behind a fake persona that appears mild and unassuming.
"Richard is a freak of nature, a self-proclaimed enemy to human kindness, bent upon destruction and the disruption of the commonwealth. As a result, Richard III is part morality play and part melodrama: Evil versus good. While Richard's Evil is writ large, the good side is sorely undermanned until the final Act."