There are those who, having lost the race to outrun their guilty conscience, abandon themselves to reckless disregard of other people's standards and expectations. Zachaeus had robbed and cheated his neighbors, and so earned the reputation of 'sinner.' On the face of it, those who called Zachaeus sinner, were respectable people. At least they did not offend common decency. They did the right thing, and managed thereby to be counted by their peers as righteous.
Jesus accepted as a fact, that Zachaeus was a sinner. Moreover, he said that, being a sinner, Zachaeus was not a person to be avoided or isolated. Instead he was precisely the type of person he had come to seek out and save. Such is the logic of God. We are not naturally drawn to people with glaring faults. Our instinct is to shun them because they offend, or fail to please us. But there is no redemption for anyone at all unless others are willing to come to them and love them.
No one liked Zachaeus. As far as they were concerned he could 'go to hell.' What is more, they were annoyed when Jesus took an interest in him.
The trouble with God is that he has an annoying tendency to value people we have judged unworthy. His love for hopeless cases seems ill-advised. But it changed Zachaeus, and unless we choose to participate in Jesus' extreme way of dealing with ne'er-do-wells, we shall make ourselves foreigners to that which alone gives us hope.
"All the people saw this and began to mutter,' He has gone to be the guest of a sinner" (Luke 19:5-7).