Yeah, i agree with you, definitely not something that should be done on screen. It's just not Den, most of them are using family and friends within their sales pitch as somehow a confirmation that the product must be good so buy it, if it's good for me, family and friends then it'll be good for you. It also the same with the way the name drop or use celebrities during a sales pitch, ok some might be shallow enough to fall for it, but really how gives a **** what celebrities think, buy or wear. It's now just another repetitive and boring part of their sales patter.
What's funny though is, they also contradict each other with it, on the one hand you have the likes of Den & Sally (she had her phone out ordering stuff during one show) buying stuff during shows and on the other you have Mason stating they are not allowed to buy until the end of the show once viewers have had a chance to buy (it's now a permanent part of his sales patter in the never ending saga of the reason he waited 3 years for his Vostok as they always sold out before end of show so he could buy).
Imagine you're in a shop and the sales assistant (which is really what IW presenters are), while selling you a mattress then suddenly decided to stop and go off and buy the mattress for themselves, it's bad manners and rude. The presenters, like sales assistants in shops are there to sell and aid customers they are not supposed to be customers themselves while they are working.