I don't think that the start of the drama shows people's perceptions about Proctor changing due to his affair. I think that it is known, but it is not something where he is viewed like Hester Pyrnne from The Scarlet Letter is viewed. Parris realizes "something" transpired between Abigail and Proctor. This is evident in the first scene where he is asking her questions about why she was dismissed. Proctor is perceived as "different" from others in Salem because of who he is. He does not live in the town, but rather on a farm outside of it. He is outspoken and not very willing to acquiesce or to conform to the expectations of others. He has a reputation for a short fuse, to an extent, and his physical size makes his predisposition to using force something that helps to cause the perception of him being outside the norm. This is not something that is enhanced by the affair, as it is not something of which there is immediate discussion. It is known, we presume, but it is not something that defines him. In fact, we only really know the full extent of how others feel about it during the trial in Act III, when Francis Nurse is floored by Proctor's admission. At the start of the drama, this is not as evident.