Yes clearing the browser cache can help with redirect issues, but a virus? Really? It’s more likely the user is clueless.
I recently clicked "BIN" on a eBay listing for a beautifully toned Morgan that was very clearly mistakenly priced. As soon as I clicked it, I messaged the seller telling him I knew it was a mistake and that he could feel free to cancel the order and relist correctly. I've mixed up coins twice (in 15 years) to recipients. Both times the sellers were honest and I gave them both an ASE for their trouble. Just do what's right and be good to people. Not much worse than a thief.
UPDATE: Got the coin back today. Mailing him the right coin in the morning with free bonuses and my deepest gratitude.
Nice to see there are honest people out there. We ALL make mistakes. You are judged on what you do to rectify it.