Two of the three badge grommets have obviously been tampered with. What badge and serial number on the bass drum?

Any idea of what could have happened? But they look like 3 plys ludwig shell, right?

Additional pictures of the entire kit will be helpful as well as badge/serial information for the bass and any other drums in the set.

The badge grommet on the kick drum was definitively heavily tampered.

Badges tampered with to that extent can not be considered reliable.

Looking at those grommets I'd suspect that someone wanted a "Ringo" set and did a rewrap on random 70s drums. From 1970 until around 1992 that was the only version of Oyster Black that you could buy. I can't think of any other reason someone would have futzed with the grommets to that degree. None of this really effects them as far as drums as instruments but would definitely put them into the "player" category which does have an impact on their value. And I could well be wrong but those questions are going to be in the mind of any potential buyer.

Anyway, as mentioned above, with grommets like that the serial numbers become meaningless (more so than usual) because they may not be the original badges.

This is why it's very important to provide us with detailed pictures before making your purchase. The badge and mangled grommets are a dead giveaway that there has been skulduggery involved. Of the three kits you posted the other day, based on the pics I saw, this would have been the kit I would have chosen. In hindsight, it wouldn't have even made the list. There is almost zero interest in this type of kit on the collecting market. Those "little" details make all the difference when it comes to authenticating a vintage drum set. I hope you can get your money back or at least that you didn't pay much. On the other hand, you mentioned your main interest was in the sound, so maybe those drums sound great. If that's the case, then congrats. If not, then my condolences.