Some people have noted the apparent faint whisker, and with other characteristics, including the strength of the eye-line behind the eye, and the lateral crown-stripe, and conclude that it is a Black-whiskered Vireo.
Others note the large, pale pinkish bill, and faint yellowish wash across the flanks, and conclude that it is a Yellow-green Vireo. The apparent whisker may be an arrangement of feathers that allows grayish feather-bases to show.
I photographed the bird at about 1200 meters elevation on the west slope of the eastern cordillera of the Andes in Cundinamarca, Colombia on August 29, 2017. At that location, Yellow-green Vireo would be more likely than Black-whiskered, the latter being more common further north.
I would appreciate opinion. Currently, I'm leaning toward the Yellow-green Vireo, mainly for the pale bill.