Salinas did not anchor the broadcast Tuesday night but did appear in file footage in Telemundo's report on her relationship with Villaraigosa.
"I think Telemundo is going to have to really take a hard look at this," said Castaneda, who has conducted research about Spanish-language media. " It doesn't reflect well. Telemundo has no excuse."
On Tuesday, most members of the City Council either declined to comment on Villaraigosa's confirmation or said that it was his own business.
That contrasted with hundreds of readers who left comments on The Times' website, with some agreeing that it was a private matter while others arguing that it showed a lack of integrity.
"He has no right to privacy in this matter as he already made a public spectacle of his family values on many occasions," one reader wrote.
Another reader posted the opposite.
"I don't care who he sleeps with, I care how he runs the city."
Times staff writers Hector Becerra, Anna Gorman and Sam Quinones and researcher John Tyrrell contributed to this report.