I responded to you on the Rickenbacker thread when you asked if getting a bad Rotosound string was "still a thing," but here it is copy/pasted:
Yep, still a thing.
I quit Rotos around 1993 due to always getting a bad string pack after pack.
Around Christmas I bought some Roto RB35 nickels to try along with some new RS66LB stainless roundwounds. I wanted to compare them to some GHS RC-L3045 and DR Pure Blues Victor Wooten 40-95 strings. But wouldn't ya know it? The RS came with a dead E string.
The Roto RB35 strings are ok; the output is quite a bit lower electrically (not acoustically) and they do have that Rotosound zing, even being nickel plated. Quite a bit around 800hz with a nice peak. Still didn't knock me out though.
What did, though? I never would have anticipated, but GHS Round Core Boomers were louder, thumper, and "upper-middier" than the Rotos, which surprised the hell out of me.
I did a test of 4 different strings. I cut a nut for 4 E strings, set up the neck and action, and then compared the aforementioned 4 brand new strings: Roto RS, Roto RB, GHS RC, and DR Blues.
The Roto RS was dead. Roto RB and GHS RC were described as above. The DR Blues were the most polite, with definitely the most fundamental. Not bad at all, but a bit colorless and bland; not much mids, but not exactly scooped. And they feel looser than their 40-95 gauges would indicate; they are almost too loose in that they don't ring substantial enough; the others (of the same gauge) don't have that issue.
I was surprised and blown away that I preferred the GHS Round Core Boomers, especially electrically...they have a big lower mid grunt the others didn't have, waaaaay less finger noise than the Rotos, and just as much upper mid attack while feeling much, much smoother than the Rotos (and on par with the DR).
But I digress. Yes, getting bad Rotos is still a thing.