Do your speakers bite??

If my speakers were to ’bite’ I’d either get new speakers or more synergistic components. Most what you call ’bite’ is, IMHO, not much more than equipment which has a peak in the upper mid range utilized in a band aid approach (cheap & easy) to getting a more pronounced sense of imaging, both width and especially depth.

Yes, I want loudspeakers that have some jump and aggression when called for, but I would never use the term bite. 

There’s a curious phrase audiophiles use for speakers with well defined leading transients, or extra string or reed sounds: bite

Ergo, "well defined leading transients" are something "extra" as well? Speakers being transiently capable to my ears are less smeared sounding, and in effect oftentimes lend a more natural imprinting to them. In the bass region lack of smear or overhang/stored energy is characteristic of a smoothness in presentation here (apart from speaking of frequency response and flatness), as could be said for the entire frequency region really where smear is a lesser issue. "Bite" as something deemed "extra" would seem unrelated to transient cleanliness, as I see it, and more a product of something else. On the other hand what is subjectively perceived as "speed" of sound, or "snap" can be or typically is an equivalent to transient cleanliness.

Sometimes this is also extra resonance from inside a string instrument. I say it’s extra because I don’t hear the same in real life,

But if it’s an extra resonance from inside a string instrument, isn’t it what’s heard in real life from that very instrument? Real life sound is un-equalized; it’s what’s reproduced that adds that very component.

but for some speakers these are marked selling points.

I’m sure it is.

So, do your speakers bite? Do you like your speakers to bite you? What is your threshold?

My speakers are build for pro cinema use, so "bite" as a selling point would seem moot, as opposed to a perhaps more common "hifi" trick with speakers in this segment. In any case I’ve made my own filter adjustments actively, and I prefer a less trebly response because, as I you said yourself, it’s not what I hear in real life instruments. Some like more "zing" or air in upper octaves likely as a means into an enhanced sensation of detail, where to my ears it draws attention to itself.