You'd be surprised what a difference some TFR makes to that kind of job,... or even a bit of chloras & some fairy liquid mixed together (Diluted of course) in a backpack and sprayed on,.. left for 10 mins before you start cleaning.
It takes the hard graft out of the job, saves time, and gives a result that will have the recommendations pouring in.
I'd say try the TFR/IPA/etc etc, before you decide anything else,.. if you still don't like it, pass it on to someone for a finders fee.