How do negative keywords actually work?

When shopping on Amazon we are being shown completely irrelevant items because they are sponsored so I decided to add plenty of negative keywords to prevent us having to pay for the same happening to ours.
I have been spending time seeing where our ads are being shown on product pages and we have had plenty of clicks on post boxes. We added this to our negative keywords both as a phrase and an exact match yet we are still being shown, and paying for, clicks on post boxes. We know that people who are looking for these are not really looking for our items but obviously if they are just wasting time they will click on anything. How do we prevent them being shown on product pages that are irrelevant to our shoppers?

With the information you’ve supplied it’s hard to say what you should do.
If it’s an automatic campaign then I’d advise you to put the ASINS of the product pages your product is showing on into the negative exact and this will prevent your product being shown on them pages.

Could you supply more information such as campaign type and a keyword/product page example?

Thank you. It is an automatic campaign and these are some of the ASINS we are being shown on, and charged for clicks.
b075xmk1yj
b011ixng8k
b01brh951e
b01lw1azlb
b01nbxgkoc

I have wedding favours in as an exact negative term plus, wedding bunting, table confetti and postboxes. There are another couple of post boxes that we are shown on. I would have put the ASINS in but a customer wouldn’t search for the ASIN so thought that that would be pointless.

We are also running a manual campaign to the same item using exact terms that we have sold on before and even at up to £8 per click we cannot get to the top of the page. We are getting no help from Amazon as they keep telling us that it relies on a number of things like selling before, this was previously a best selling item until somebody at Amazon made it unsellable by making unnecessary changes to it. We are really struggling to get it seen now.

So on your automatic campaign/ad group I would put those ASINS in the negative as this will prevent your product being shown on those pages - so not pointless at all.

Amazon are correct, the top of page can depend on multiple factors. My recommendation would be going to your placements and increasing the bids for top of page searches.

I have had them set at £8 per click as an experiment and still hardly getting any views. I think this has been suppressed in some way. Somebody at Amazon interfered with the listing and made it unsellable so we are now fighting to get it back to where it was. It is also a Seller Fulfilled Prime item and we all know that that is the only filter that customers ever use so we should be getting more than most in the category.

Thank you for all of your help. I have added all of the ASINS from the last couple of months to the automatic campaign and upped the price again. Somebody tried to find it for me in this thread and even though it was advertised at £8 per click it didn’t show yet another item that has almost the same title, search terms and description showed at the top organically. The item that showed up doesn’t even have as many excellent reviews.

It is still being shown on the ASINS that are in negative keywords so it appears that Amazon decide where they are shown and that means on all the cheap Chinese tat. Our target market probably isn’t going to be looking at items at £2.99 with free shipping.