The expression referenced is actually "one bad apple spoils the whole bunch". So by that adage, they are actually admitting that they are all bad.
On edit: "One bad apple don't spoil the whole bunch" isn't a saying. It's a line from a 1970s song by the Osmond Brothers. Take from that what you will.
And the adage is meant to explain why a single bad apple should not be tolerated. You must excise and discard the bad apples to protect the rest. Protecting and nurturing the bad apple spoils the rest.
It's hard to gauge. It basically like reviews at a restaurant or store. You'll have hundreds of satisfied customers and maybe two positive reviews, but you can be damn sure everybody that had a bad experience will leave a one star review. Same thing with police videos and articles. You get to see the worst while the hundreds of good, positive interactions probably just never get mentioned.
Maybe it's like that maybe it's not, but I would lean towards it being the case. It's just human nature.
Wait are the police the bad apples or are the police calling the riotors bad apples. Or is a meme whatever we need it to be.