If the walkthrough involves several cleaning contractors, get there early. This may give you an opportunity to get to know the client and for them to get to know you. Be careful asking “personal” questions. For instance, it is really not your business who is currently cleaning the facility now, so don’t ask. Also, unless they volunteer their cleaning budget, most clients would prefer you do not ask them how much they have budgeted for cleaning.
I'm a former Building Service Contractor who worked in Northern California. At one point fairly early in my career, myself and six other BSCs bid on a cleaning contract for a major advertising firm in San Francisco. The facility was located in a historical district that had many old warehouses, which have since been converted into office space.
About six years ago, the professional cleaning industry was introduced to automatic scrubbers that could clean and maintain floors by electrically converting regular tap water into a cleaning agent. While there was certainly some controversy about these systems when they were first introduced—mainly revolving around claims about their cleaning effectiveness— these days chemical-free floor machines appear to be quite popular and are now used around the world.