Different subwoofer settings for different albums?

Well integrated subwoofers are invisible. Find a different dealer.

Set your sub or subs properly (not by ear in my book) and forget. The sound recorded is what I'll listen to, and with three subs down to 25Hz I'll only hear what is on the program, nothing more or less. Having that clean tight ultra-low last octave adds a lot, but only when it should. Mine are 100% sonically invisible.

If I have a recording that is just too lean, or being played too low in volume, I can use a 'loudness' type button to help add a subtle bit of low end curve. I use it for low volume listening mostly. I never touch the subs once dialed in.

In days past we didn't have subwoofer control. Your system just played the bass notes as they were produced on the album. Some albums had little bass and some had room shaking bass. Your job was to get your system to sound right and correct playing unamplified music to get the bass balance right. Once set, that was it, and you just played your albums as they were. 
Today, I find myself adjusting the bass all the time but mostly because of the Fletcher Munson Curve and the loudness level I am using at the moment. As I play louder, the bass gets turned down and gets more natural. 

Great topic.

The spinoff  thread - do you break audiophile protocol and make technically incorrect adjustments to enhance the experience?

On some recordings, listening to them on a well planned/technically "correct" setup reminds me-Yup, the recording is what it is-relax and let the sub do what it does. If you're listening in a living space and expect to hear what some are, all bets are off.

So a dealer I know told me that he doesn’t use subwoofers and doesn’t know anyone who does (!) because he finds that every record has different levels of bass and would require a new subwoofer crossover point to properly blend with the main speakers.

A new crossover point; no, a different amount of gain; maybe. Considering that the acoustic properties of your room differ from those of the recording and mastering venues not to mention the amount of contraband in use at the time, it is possible that the balance between mids and lows could be off, but it is rare. Usually it is just a few stray frequencies that are off that muck things up.