This is an excellent question as it identifies the way in which Willy's flashbacks, especially those concerning The Woman, his former mistress, indicate his guilt and shame about his affair. You would do well to go through the play and note down the occurrences of The Woman, tights and the Woman's laughter, which act as symbols of Willy's infidelity.
The first time we are introduced to The Woman however, in Act One, is in the middle of rather a tender and loving scene between Linda and Willy. This clearly exposes Willy's lack of integrity. He cannot remain faithful to the one person who is completely faithful to him, and even his hallucinations seem to emphasise this. Note in this scene how it is mentioned that Willy has given stockings to his mistress, only to see his own wife mending her own stockings. This creates massive guilt in him as he has been spoiling his lover at the expense of his wife.
Of course, this is another form of "success" that Willy dreams about to bolster his sense of self-esteem, but it is also a form of "success" that increases his guilt and forces him to confront his own betrayal of Linda.