He played the Beetlejuice laugh when Beth plugged the Bling Bones jewelry.
Robin is ridiculous to me in this regard. She's allowed her true feelings to be known about Robin from time to time (the way she mockingly read Beth's FHM interview; her saying "she's gonna throw a party!" in response to Howard saying that Beth said that she wouldn't know what she'd do if he died; her badgering Howard to admit that it's "the whole package (i.e. fame)" that attracted Beth, etc.).
Yet here she was kissing ass at an unbelievable rate. Robin obviously knows that Beth's a fraud. Why keep up the charade? I understand job security, but just sit there quietly then.
I loved Beth acting like petulant child when Howard cut her off about the Bling Bone nonsense. Funny how Howard immediately knew what pissed his princess off.