Because of the Fall, man is no longer both able to sin and able to not sin. He is only able to sin. The entire inclination of his being is toward sin and rebellion. This inherent corruption in man exists from the very first moment of his existence. Of course, when it is said that man is totally depraved, this should not be taken to mean that people never do anything positive or good, or that one is always as bad as he could possibly be.
All people occasionally do things that benefit others.
A person may do some outwardly good deed, but deep in his heart there is some motivating factor that serves the self. He does the good deed because it is expedient for himself at the time. Thus, for a deed to be truly good, in an ultimate sense, one's motives must also be good. Motivation is the crucial point at which everyone fails. A man is said to be good relative to other men.