In Apocrypha 3 (1992) 155, Christine Thomas wrote regarding the Quo Vadis scene in the Acts of Peter and the Acts of Paul (:
The points of contact between the two acts, however, betray in only one detail the exactness one would assume from the use of a written source. … Despite possible redactional alterations, however, nothing suggests literary dependence. To assume literary dependence upon this basis betrays a literate bias.
Then in 2003, Christine Thomas wrote in her monograph, The Acts of Peter, Gospel Literaure, and the Acient Novel, 39:
The quo vadis story appearing the Acts of Paul is not a citation. Rather the Acts of Paul borrowed the narrative unit from the Acts of Peter and recast it in a different manner. The relationship between the Acts of Peter and the Acts of Paul thus form an analogy to that between the Acts of Peter and the Acts of the Apostles. The relationship between the two documents is not close enough to indicate an explicit allusion. The early point of contact is a substantive one; the Acts of Paul borrow the quo vadis story in filling out its own narrative.
Thomas thus vacillates between insisting on the importance of orality and falling into a trap which she calls a “literate bias”. As I had mentioned before, Dennis R. MacDonald contradicts himself similarly in regard to the Patroclus/Eutychus story. Like Thomas, he says bias leads to the suggestion of literary dependence (“Only our Western prejudice for written dependence would make us think the author [of the Acts of Paul] picked this story out of a book and not out of the tale-rich air.”), and then changed his mind.
The parallels between the Acts of Paul and other apocryphal acts and the Acts of the Apostles is, in my view, evidence of oral tradition units that the author used to create his narrative, not from thin air or from the pillaging other acts, but from “the tale-rich air”.