As we mentioned earlier when the contents pros arrive. It is quite common for them to start with a digital photo inventory of the affected items and the impacted rooms.
Unaffected rooms are sealed off so that cross contamination is kept to a minimum. Ash and smoke particulates are not always visible to the naked eye, but under a microscope they are easily differentiated from ordinary dirt.
And soot has the unnerving property of accumulating in layers (sort of like painting a surface, then putting on a second coat). When that occurs, special sponges and solutions are used to break down the bond and remove the particulates.
Smoke odors are another matter. Ash residue travels. Just walking through a room can create unseen disturbances in the air, so special “air scrubbers” are employed. Then the professionals seek out the sources of the odors and treat them with specialized solutions, hydroxyls, foggers. And a few favored methods to test and retest before considering the job complete.
The last thing they want to hear – or to hear about from agents and adjusters – is a complaint. That the odors are still present (or have returned) after the team has moved on to another job.