I agree, to an extent. If you are looking for a "touch of chorus" or "bit of hair" then yes, the audience probably wont specifically detect those effects ("that overdrive on that bass sounds good").That isn't to say that adding a touch of this or a bit of that doesn't improve your overall bass tone ("no matter what, it sounds like bass"). They may not detect "chorus" but the bass tone is improved (for some reason the listener is unsure of). And of course, the "improvement" is subjective.
Now, if you add a much more wet effect, I think it is definitely heard in the audience. Geddy's overdriven Ric/Jazz is heard and is black/white vs. a pristinely clean Ric/Jazz tone. An envelope filter is distinctly heard if it is wet enough. Same with a phaser.