This story has been recounted by all four narrative gospels. There are significant variations in the four versions, yet there is also remarkable agreement on the basic ingredients of the tale. The setting of all versions is a meal, or symposium, at which the owner of the house is present. A woman anoints Jesus during the meal (not before or after it) with a jar of perfume. Members of the party object to the woman's action and Jesus defends her. The similarities in the setting and plot suggest that one incident or story lies behind all four versions. Yet because of the variations in other details, the Fellows of the Seminar decided that the original version of the incident is irretrievable.
Lüdemann [Jesus] (94) comments on the Mark passage:
The historical yield of the tradition is nil. But it does reflect the closeness of Jesus to a probably notorious woman of Galilee (cf. on Luke 7:36-50).
In his comments on the Lucan version, Lüdemann suggests that Luke knew the Mark story yet deviated from his usual practice of following Mark closely in the passion account in order to bring this story (in an amended form) to an earlier location in his Gospel. He notes the addition of explicit mention of the sinner status of the woman in vss 37 and 39 (and the forgiveness of her many sins in vss 47, 48, 49). He then concludes:
If the story of the woman who was a sinner must be regarded as a mere development of Mark 14:3-9 it is unhistorical. But as the encounter of Jesus with a prostitute comes from the Lucan special tradition, this may be historical. For the contact of Jesus with shady people is a fact. The historicity of the encounter of Jesus with a prostitute is supported by the criterion of offensiveness. (p. 308)