Thanks for all the replies.

Yes, Colorado Springs is [still] correct. The dealer, Bob Penkhus Volvo[-Mazda] has (well, had) done excellent alignments throughout the life of this car (which spans more than one alignment rack there). But on my Mazda (my previous car), their service manager there (many service managers ago, back in the 1980s) did deny me warranty coverage because he felt that causing an intentional cross-camber alignment condition (because 1 alignment was covered under warranty) could offset the symptoms of a power steering rack which had power assistance in only one direction. That fiasco got properly handled only following the installation of a newer/better/different service manager...

Installing the left mount/boots brought the car back into balance, the rights having been done on separate occasions as needed over the previous several years. When the more compliant struts were installed last November, the original left upper strut mount was still nowhere near needing replacing, though it did sport a tiny old-age crack or three.

Worn parts undoubtedly exist throughout the suspension, but the steering was day-and-night different (incl effort and [anti-]self-centering) before/after the November service (struts, boots, mounts, alignment). It's stayed different, too. Right now what I'm sensing is worse, but this is following the most spirited, er, diagnosing I've done with the summer tires mounted since then, and they're significantly feathered now, so what I feel from the driver's seat is more pronounced...

Yeah, the Ackerman angles are (supposed to be) built in, but the positioning of the front spindles/hubs/wheels is apparently no longer being precisely and correctly maintained while turning. I's almost like I can feel my precious tires graining in one turn if I dare explore any part of the performance envelope, but that's probably 'just' the feathering.

I'll get out a tape measure (I've never tried that; toe was way off after the 1st alignment following strut repl, but that was attended to, and tracking and mpg improved afterwards). Bilstein's Scott McDonald (East location) was thinking along the lines of loose steering rack or crushed control arm bushing or even if the nut was not tight on the spline (that one both scares and resonates with me). IOW, something which permitted some locator of the front wheel's precise position and thus steering geometry/angle to slide along some axis. Given the sideways component to how the steered wheels bite in a parking lot situation, that tends to ring true to me. (If wheels were to slide/move farther apart [an increase in track width] and they're steered from behind, that'll cause a toe-out condition, right?)

I guess I'm of the opinion that focusing on readings/settings while stationary on an alignment rack is probably a bit of a distraction, if some floppy imprecise variable alignment when turning is but a symptom of some cricical component's extreme slop/variability in placement while under load during use. When the alignment rack, during routine calibration/setup, tells the operator to turn the wheels, are the Ackerman angles being closely checked? If they are, could the operator/technician simply ignore any such indication and proceed with the alignment as if everything was fine when, in fact, the machine already knew (and had tried to tell him) it was not?