This was a couple of years ago but I remember watching Marlo on HSN one night and it was so frustrating. The vendor was explaining something and it was like Marlo wasn't even listening because she would interrupt in the middle of his thought and ask other questions and make random comments. I was really wanting to hear the end of the vendor's story. Well, the next week she was on and she said that she had received complaints about jumping in. She said someone asked why she just didn't let the vendor speak. She said what we didn't understand is that they are trained that the presentation should be like a back-and-forth conversation - always. They are taught not to just let the vendor speak.
In my opinion, that's bad training. We can learn from the vendors (especially computer presentations where they are showing how to do something). SK interrupted an iPad demonstration once right when the vendor was getting to the important part of how to do something. She changed the subject and the vendor never got to finish.
I think the hosts could all stand a refresher course or two but apparently, our opinions do not matter.