We gave up looking at used and got a new LRY for the exact reasons you stated, the stereo and the range reduction in the RWY totally devalued the whole car. I would never buy a used Tesla from Tesla, go direct to a current owner, you will always get a better deal, especially if you are as discerning as you are about the cosmetic stuff. Over the years my driveway has had 5 "eBay Queens", bought using the following terms; vehicle you want + divorce or bankruptcy or separation or estate sale or moving out of country. It takes some time and frustration as some people (mostly used car dealers) just outright lie about the condition or specific information about the car, I recommend just excluding the dealers from your search. All the successful "Queens" were bought direct from the original owner or family member.
The best deal I ever got was a wife who sold her husbands motorcycle while they were separated. New Honda 2004 VFR800 VTEC with 480 miles on it for $6200 dollars in 2004. The hard case panniers on it alone where $1.5K, and came with 2 new helmets, security lock, cover and bunch of VOX operated communications gear. She was also selling his BMW, but I had no interest buying an M something.
Also bought a 2014 P85+ bought in 2015 for $69K, estate sale with 9K on the ODO, the P85D had just dropped so it was an excellent timing event for an awesome RWD performance S, just sold this car with 112K on the ODO for $36K last year. New 2007 FJ Cruiser with 1800 miles on it for $22,900 in 2008 from a kid who got over extended, still have it. A new in 2014 Grand Touring Miata for $9K with 1400 miles on it, fresh water damaged (guy left the top open during Katrina), changed out one electronic control unit under the dash for $250 part + $150 in labor and it is still in my driveway 10 years later now with 75K miles on it, Zero FX Motorcycle with 400 miles for $6K, new it was $12K, 8K later still have it.
If you can't go look at the vehicle you can have eBay do it for you and provide a report for ~
$100 through a company called SGS. Dealerships charge that for "paperwork" or some other BS useless charge. You know you are on the the right set of cars when the other guys looking at it are broker buyers.....just over bid them and a you should be GTG.
Your concerns are justified, don't walk, run away from this "deal". There are some nasty un-hygienic people out there, I would never buy that car, your nose told you everything you needed to know.