Cleaning old PCBs & ESD

[Adamus]

I would love to see a video about all facts which are important during cleaning old PCBs.
Sometimes we want to take apart our electronic equipment (even a plain PC) and clean it (you know, Christmas, etc.) before turning it on .
Should we always use only those ESD-Safe brushes to clean boards and nothing else? Can we use a simple paintbrush (which hair?) or a toothbrush instead? Is it allowed to use a dry/wet(IPA) paper towel, Compressed Air Duster Can, hairdryer or just an air compressor without additional precautions?
Dave has an ESD meter which may help to answer some questions.

Bonus part could be about anything water-related (& rust) during cleaning. IPA is my favorite choice, but some GSM people say "use a mixture of water & detergent to remove sugar at the very beginning".