I think the inspection goes a little faster without the seller or their agents present, but it makes little difference to me if they are present.
My inspection and report is the same unless I can get reasonable explanation concerning something that I have a legitimate question about.
If I feel the owner / agent is getting too intrusive, I will pull my client aside and explain things privately.
Just Friday, I had buyer and wife present and trying to explain about the sellers hatchet job on the electrical in the attic. I let the seller explain about what he had done and how he would restore it if the buyer wanted, I just nodded and smiled.
Then out in the back yard out of earshot from the seller, I explain that he needs a licensed electrician to fix what the seller had done, even if he had already "restored" it.
This seller also had installed a vent hood, propane hot plate, and cabinets in the garage. It looked pretty good until I found the vent hood choked down to a 3" w/h vent in the attic and the propane bottle connected and stored in the cabinet below the hot plate.
I get paid to inspect and inform my client, confrontation with the seller is not included in the price.
Some people (inspectors) enjoy the "banging head against wall" scenario, but I don't. I don't have time nor the energy to waste trying to teach the seller (unless they are my client) how to fix what they screwed up in the first place.