In what circumstances will we show deference to an agency when it does not purport to speak authoritatively?

especially disinclined to defer to an agency when it does not purport to speak authoritatively. In the past we have declined to show an agency deference when "there is no indication in the record of the process through which [the agency] arrived at its interpretation" and the agency itself "labels its interpretation as `tentative' "because "we cannot say with confidence that [the agency's] interpretation came about as the result of a reasoned process." Rabin v. Wilson-Coker, 362 F.3d 190, 198 (2d Cir.2004).