It’s too bad variable venturi carbs didn’t see greater use in America, a greater experience with them might have prevented some negative vibes.
The SU carb’s reputation undoubtedly was sullied by those more used to mechanisms of poor running associated with fixed venturi carbs. SUs - kept clean - are as close to set-and-forget as one could ask for. And with some modicum of understanding how they work, they’re not hard to set up.
My own long experience with these things is that distributor faults make their presence known long before the carbs complain in SU-equipped cars. But for mechanics weaned on the fixed venturi carb, the zillion intricate parts and passageways of the fixed venturi carb give problems before the diz can, so that’s of course why the attack on poor running was aimed at the carb for the mechanic used to American cars. The learned relationship of poor running with the carb meant those poor SUs suffered the attacks of the misdirected, when in fact the problem lay with ignition. Once meddled with, without an understanding of how they work it is indeed very difficult to tune them well. And then having created bad carb tuning, even if the diz is finally addressed, the engine still doesn’t run well because the SUs have been molested. A viscious cycle ensues, and hence a bad reputation for the SU and more generically for the cars that wore them.