Suppose you wanted to mess with a forensics class, if the perpetrator gathered dust from a public building where hundreds or even thousands of people pass through on daily basis, let's say someone has a small portable vacuum for crumbs and goes around public transportation, gets dust from the vacuum in a supermarket, hospital, municipal building, a police station (bonus points) etc. and then used this skin flake laden dust to contaminate the shit out a crime scene.

Would it throw a wrench in the forensic process? Would they have to sequence thousands of DNA pairs or could they differentiate more fresh skin flakes somehow?

And if they did sequence those hundreds of DNA strands, linked them to individuals and then were able to discard a lot of them quite fast, what if it contains dust of basically all spouse and relatives statistics would suggest are usually the perpetrator?

For instance, 90% of spouse being killed is done by their partner.

In general how could you mess with DNA forensics?