Unable to audition used speakers a problem

I agree, it's supicious at least that a seller will not allow audition, but your choice is not to deal with that seller, and he/she must realize their unwillingness to accommodate a potential buyer limits their market. On the other hand, if your intention is to troll around and listen to speakers before you're really committed is going to be viewed by most sellers as a waist of their time, and rude on your part.
I generally would provide an audition of ANY equipment I'm trying to sell; but would qualify the buyer's readiness and commitment before hand.

As to whether you're overly prudent - I have purchased and sold many used components as a means of performing "in home" auditions. That's one of the great things about the existence of a well established used market. You will learn a lot more about the speakers and make better use of your time IMHO by doing it this way. And if you're careful it may not cost you much or any $ out of pocket - although really heavy speakers can be an issue with shipping $, or are limited to local sales.

I agree.

I audition all the equipment I sell locally to avoid problems in the future.

Lots of reasons starting with privacy/security, lack of front end gear, not wanting the hassle of tire-kicking fruitcakes coming around, and simply wanting a quickly transacted sale. Your reservations are noted but it is an agreement between two parties that constitute successful sales.

Many spkrs have enough reviews and internet buzz that you pretty much know what you're getting before the fact. And how many dealers let you take valuable stuff home [and off the sales floor] for an audition? Sure, you can listen in the store with unfamiliar equipment in an environment almost guaranteed not to be anything like your own room, and with unfamiliar material if you didn't bring your music. Yes, lots of pitfalls in the spkr buying game. One recourse: after you buy, break them in, tweak and listen for awhile, you acclimate to the sound and often end up liking what you bought, albeit in a back door kind of way. Good thread.

I understand what you are saying, but most sales I have encountered here on agon always required shipping.
Think about this:
You buy a new set of floorstanders to replace the old ones.
Do you really think you have room for 4 speakers in you living/listening room?
Then there is the fact that you have twice as many speakers (4) & probably more boxes (6) & you better half is on your case.
Good point on the privacy issue, but not a issue for me - but space is!
I just pack them up, put them in the garage & save twice the room & they are out of the way until the phone rings or a serious e-mail comes along & my wife is happy.
Always best to do your research/auditioning first & then jump on the right choice @ the right price & take 'em home - but do take them out of the boxes & check out their condition first.
Since the seller is local - Have him/her agree that if there is a problem or serious issue - He will take them back within a 3 day period.
I have shipped (sight unseen) to California, Maryland, Canada, UK, Germany, Italy & Spain with no problems & 100% positive feedback.
Hope this helps in your quest