I too believe it is commonplace and (not where I work now) but in roles I've had in the past, I've known people have done it. I've always taken the stance that it's something no-one should accept, for issues of pragmatism as well as honesty; I fervently believe people always get found out in the end.
The site which is prepared to falsify records thinks everything is ok when they get their BRC grade A, PIU green / blue etc but in reality it's not. Where is the impetus and pressure to improve the system if you get great audit results? Falsifying records is naive.
With the pest control example, I would have made sure the actions were actually completed then complete the last record, not go back. Auditors do expect to see failings in a system but if you've found them and resolved them yourself, that's something to be praised. It would be a picky and ineffective auditor who raised "you used to have a problem with x".
The PP has a good point. If you went to court over, say a metal find in a product, your metal detection records would be used as evidence. If you had the Topic Bar mouse issue, your pest control records would be evidence. Do you really want to stand up and defend something in court perguring yourself? Or would you be prepared to stand up in court and say "I was a bit embarrased that we'd not weeded by the fence so I pretended we had"?! 