There are some things that our clients can inspect without us that don't requirement a blower door or duct blaster. My favorite is the frost assessment first thing in the morning. I tell my clients to look at their roof when there is frost out and if any of it is melted BEFORE the sun comes out then they have heat and energy loss. A blower door is a good follow up test to this DIY visual.
This can also be good for marketing. Do this audit AFTER the work is completed and show the Before and After or just compair it to the neighbhors house.
So much of what we do may appear to be Vodoo to our clients and simple visuals such as water turning from solid to liquid is an easy concept to understand.
What other DIY measures do you all have your clients look for to know if they have issues before you come out?