A small steam cleaner with about 4 bar pressure will do lots of little jobs in awkward areas such as behind radiators, corners of windows, behind pipework, toilets, sinks etc.
I use a small steamer on general EOT's to make life easier for me as my fingers wont fit in those cracks anymore. It's especially good around pvc windows when cleaning out all the little grooves and gullies. I wouldn't consider doing the whole house with it and certainly not paintwork on walls.
Removing cobwebs is best done dry as they stick to the wall and make a laborious job even harder, although the guy I work with loves to blast those little devils. I have taken to getting him wiping the damn things off the walls himself and he has since abandoned the idea.
As far as oven cleaning is concerned you need to pre-spray and use a decent steamer with a wire pad over the steel brush otherwise you are on a hiding to nothing. It simply hardens the crust of fat (I wonder how many chips you eat in 10 years?).
Sounds like the cleaner was great with the old BS and simply touched up the clean with the steamer.
I have never used a fogger to
"clean" an EOT?!? I hope I don't have to as I only use them to sanitise and deodorise in specialist cleans. Heaven help anyone who has a house so minging it needs fogging when the tenant moves out.
Just get a little 4 bar polti (not a QVC or ebay special) and give it the old blarney with the client. It's amazing what effect a cloud of steam can do raise your standing in the eyes of a client.