For me, it depends on how much they are charging, what they do, and if the end price is acceptable to me.
When I bought the clipper, I balked at the $800 charge for the "full" PDI, but had them plug in the shore power so I could test the fridge. They charged me $200 on paper for that - but I pulled out the brand new $200 converter/charger in the TT I was trading in, so I wasn't really out anything.
I also had them include a clause in the contract that if I found the fridge wasn't working properly within 48 hours, that they would remove it and put in the working fridge from my TT - figured that was a good compromise for the most expensive potential issue. In the end, everything worked great with a minor fix (replaced thermocoupler in the fridge). When the charger portion of the original charger/converter stopped working much later, I used the one I pulled from the TT and saved that expense.
So, in the end, it just depends on the bottom line and your risk factor.