Images like this show how specifically the antibody binds to the antigen. Generally, the ideal is to have very specific binding. As such, this type of image (Western blot) would only have single bands in any vertical lane. Any other bands show that the antibody is binding to other molecules.

The evidence of painting out the background is likely someone cleaning up other bands, where the antibody has bound to something other than the intended target. So, they are making out the antibody is better than it actually is.

Copy-pasted bands could be evidence of attempting to make a weak band look stronger, or even adding a band where one didn't exist - potentially the entire blot is fabricated.

Either way, like someone else said, this is like fabricating parts of a data sheet.

It doesn't excuse it, but like someone else said, scientists would never just trust an antibody they bought. They'd do their own tests. Labs will also share notes amongst each other, along the lines of "that antibody is bad, and also strongly binds XYZ. You should try this other one instead".

From the article:

> This image is supposed to demonstrate that the antibody being sold works as intended. (…) Antibodies are near-ubiquitous but notoriously fickle laboratory reagents in biomedical research. For many applications, it is absolutely crucial that the antibodies that you use are selective (i.e., the antibody binds strongly to the target protein) and specific (i.e., the antibody binds to the protein of interest and little else).

Antibodies showing a different picture (Western blot) than what is expected can drastically change the interpretation of the results as well as the conclusion of a study, for example. It may also encourage scientific fraud by authors by forcing them to unknowingly/coincidentally make to a blot image the same (or similar) fraudulent modifications performed by the vendor.

Now I’m curious about how much of the blot photoshopping present in retracted papers can be attributed to these misleading verification data.

This is 'used car salesman' levels of fraud on that scale. People rapidly acknowledge these antibodies work or they don't. There are websites with reviews of them. However in addition to getting ripped off for a few hundred bucks, these antibodies are generally produced by immunizing animals and by faking this data they are unnecessarily increasing the discomfort to these animals for a fraudulent reason. Look up the Santa Cruz antibody scandal for more of that.