Someone's random article from a non-ranked journal, but looks like it's got some decent reference papers http://www.jimsjournal.org/13%20Yi%20Ching%20Tsai.pdf
A google search provides very little studies that address endorser on perceived quality of the product. The couple I found provided mixed results, with questionable applicability to western audiences (E.g. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2814907).
Those who are asserting that its obviously true that endorser influences perceived quality apparently do not have the literature behind them.
Do you have something to back that up? Curious if this is true, or just your perception.
Consider the possibility that all basketball shoes are substantially identical, and that Nike is paying LeBron $1B simply to differentiate theirs.