It's the % of negs that matter and this person has 97.7% positives. But if there are any negs I always read some of them before buying.
search "ebay" and "YAET" here and you'll find dozens of threads where jerk buyers are leaving negatives that the seller didn't deserve.
Many eBay buyers are scammers ("ship your laptop to Paraguay, yes?"), ignore the terms of the auction, try to change the terms, try to back out of an impulse purchase, don't know what they're buying, etc. etc. so over time any bulk seller will pick up negatives (many more than "3 strikes").