Nope, you'd be shocked at what you'd see at high-end manufacturers selling products in the $5,000 to $100,000 range. A front office full of marketing clowns schmoozing with reviewers, and a harried tech in the back room that's actually doing the real work. One real engineer who is well-hidden from the public is the norm. The multitude of design errors that slip through is why "modding" high-end works so well.
One of my good friends, with an RF background, went through a famous-name tube preamp with glowing reviews from all the magazines, and found that *all* the regulators were oscillating in the 10 MHz region. Not synchronously, mind you, but each singing their own little tune, and modulated by the audio signal, too, as the current demand through the regulator changed. Really pretty front panel, though. He told me that oscillating regulators is the trademark of that company, and the reason for the "bright sound" that reviewers love so much.
One of the nasty things to look out for in any feedback amplifier, particularly ones with tricky SPICE-optimized feedforward elements, is intermittent oscillations, or put another way, not quite enough phase margin. Designers forget that phase margin is affected by the reactance of the load, which in turn affects settling time. If an interior element sees a reactive load that is dynamic - like the gate capacitance of MOSFETs - the preceding stage can momentarily lose stability. This kind of thing is very difficult to see on a scope - at best, just a whiff of blur, and you won't see it on a digital display at all. The designer needs to use a wideband spectrum analyzer that can peer into the noise, and look for spurs where they don't belong.
Another way to winkle out incipient instability is remove all the lowpass filtering from the input section of a linestage or power amplifier and send an ultrafast pulse into the thing, just short of clipping. Poorly-designed amps will blow up, of course. Too bad for them. Assuming they survive - and they should - you then look very carefully at the rising edge of the pulse, especially towards the top, at every stage of amplification inside the amplifier. That, and the settling time of the pulse, will tell you a lot about how stable the amplifier really is. Repeat the pulse test with reactive loads that simulate fairly long speaker cables and complex crossovers, and you'll find which amps sound good and which don't.
