I probably play the thrill is gone by BB king a little bit different every time I play it. I'm sure a lot of it depends on how aggressively the band is playing. If the bands playing very laid back I play with the very laid back tone, if the bands playing aggressive I'm my slap it with my thumb to get a little growl.
For me that sounds like how the blues should be played, expressive and in the mood.
I dono, it may be my age, it may be due to the music I grew up hearing. For me it has always been about improvising and making it your own (
unless you are in e.g. a tribute band, which e.g. dresses up to give the audience the illusion they are seeing/hearing the originals).
Aside from Blues/Soul/R&B/R&R/Brit Invasion/Folk & Folk revival/Trad country/Rock/Funk... I grew up hearing pre hard-bop jazz
constantly in the background, and later when my journeys took me there in the foreground. My step dad had been a jazz drummer and was a huge jazz buff, rare when it was not spinning on the turntable.
Many of the "Jazz Classics" were origionally really flat and often horrible pop/dance/schlager tunes, which the musicians took and made their own and spectacular. There were of course many others which were also composed specifically as Jazz tunes with open space for the soloiists (especially Ellington/Henderson). Each musician interpretating it very differently and uniquely. Think of Billie Holiday or any of the Cafe Society bands & musicians. None played it as it was in the original.... often in those cases fortunately. The same is true of Blues/Soul/R&B... Think of Aretha, she never sings the same tune twice the same way, even her own self written songs. The Jump/Country Swing/Doo-wop/Rock 'n' Roll bands were doing the same often with a riveraly competing back and forth each trying to outdo the other with the same songs.
I'm
not critizising what a cover band now appears to mean/be, you can learn and perfect your technique a lot by copying your role models exactly and there are apparently eager audiences who want and perhaps now demand to hear it played that way. I just wonder when this started, I fear I missed that bus when it came by.