Are they serious?

[Dynacord]

Yes, Sweden was certainly different. I was in San Francisco where Leo Quan/Badass was local (I remember him in the back of the shop Satterlee and Chapin) so they were very commonly used in that area and era. Similar with Stars Guitars (same building then as Modulus Graphite) and heavy brass hardware.

 

[MobileHolmes]

re: the Badass bridges - the first version before the Badass II must have been late '70s and that one had to be countersunk on Fender basses. I worked in a repair shop in the '80s-'90s and saw many otherwise original (including pre-CBS) Fender basses which had had this done (granted, it was still possible to find '50s and '60s Fenders for less than the cost of a new one in the early '80s). Same thing for guitars with the Floyd Rose/Kahler fad - I still remember a near mint '56 strat with one and locking nut... The Badass II was an improvement in that it didn't require permanent modification (though would sometimes leave fade shadows in the lacquer if going back to the original bridge).

I don't get too hostile at people that modded vintage instruments, because, for a while, they were just old basses. Heck, I remember when you could get a 70s J bass with blocks for about 250 bucks. I will say, though, the countersunk badass just makes me sad. I've had them. They're fine, but I don't see any real advantage of them over a stock bridge, so it just seems like tearing up an instrument for no real improvement. At least a Floyd was a functional upgrade in some ways from a strat trem

 

[Dynacord]

At least a Floyd was a functional upgrade in some ways from a strat trem

I guess I should mention that on that particular strat the 'installation' was done at home with a hammer and chisel (seriously). It was stunning. Not in a good way.

 

[MobileHolmes]

I guess I should mention that on that particular strat the 'installation' was done at home with a hammer and chisel (seriously). It was stunning. Not in a good way.

That hurts my soul

 

[Dynacord]

That hurts my soul

Mine, too. Also saw a 1960 Les Paul flame top that someone made into a double cutaway with a bandsaw. Countless Fenders that had custom colors removed for the natural look in the '70s (one that stands out was an early '60s strat which had original seafoam green under the guard and in the cavities; and a '61 jazz bass which still said "Oly White" in the pickup cavity but had been sanded and carved but still had all the original factory GOLD hardware - super rare, especially on a bass, for that time). Those countersunk Badass bridges were a real waste IMO but it was pretty common (where I was). Also a lot of added pickups - like a third jazz bass or mudbucker, etc at the butt of the neck.
I suppose this is part of why original examples are worth a lot; there was quite a bit of attrition due to people not leaving well enough alone.