I've been working on and building computers for over 30 years and have never had an issue, although I am aware of ESD, always touch the inside of the case before touching components, never handle the socket part of a component (hold it by the edges), and don't run around in silk socks on a wool rug.
You really don't need to disassemble to clean, just use canned compressed air and a small unused paint brush to gently brush surfaces -- I also use a small plastic vacuum attachment to suck out dust bunnies on the bottom of the case and to clean the fan filters if there are any.
I would say that if you are aware and careful it is not an issue.