Do you think audiophiles are the most gullible hobbyists

If you are thinking about being gullible regarding fuses, cables, cords, etc, no.  I haven't felt as if I have been deceived on any of these items--they have all worked to improve the sound. I am skeptical of the magic dots and stickers, though.  For music purchases, it's not that we're so gullible as it is willing to take chances on a better issue, etc.  Comparing hobbyists to just being consumers, people are much more gullible in buying weight loss products, beauty products for skin, hair growth products, get-rich seminars, healing pendants, televangelists, etc.  Audio gullibility pales next to these attractions.  

I don't know about audiophiles, but car wax enthusiasts are certainly up there.  There are numerous waxes selling for thousands of dollars for one jar and the better "enthusiast" waxes go for a couple hundred for a jar.  I don't want to say these people are gullible, but it may make you feel better about spending a few thousand on a set of ICs, which at least will last for quite a few years. 

Ions ago I had some really professional sales training, where they differentiated "need" from "sense of need".  To highlight the difference they gave an example of one being a salesman selling house painting services, in a neighborhood where one house was very neatly kept, had a paint job that was a few years old, starting to fade and get dirty, while the house next to it had badly peeling paint, noting that the latter had a real "need" for a new paint job, but the former had a much more powerful motivation or "sense of need", and would be the customer you would be best to concentrate your time and effort on closing the sale.

Our hobby is definitely one of those "sense of need" scenarios.

We've all got to admit that it's really a lot of fun to swap out equipment and accessories and see how that changes (hopefully improves) our musical experience.

Hey, if some of the crazy things that audiophile purchase make you happy, that's all that counts!

As to what thing seems preposterous, too preposterous to ever consider, I suspect it all depends on the thing being considered and the person doing the considering. There are a lot of things in audio that were once considered absurd or preposterous that are now commonplace or at least relatively common. Things like vibration isolation, tiny little bowl resonators, hi res downloads, WA Quantum Chips, Schumann frequency generators, CD enhancers, CD demagnetizers, cable elevators, fuses with directional arrows and scattered laser light absorbers. I admit Mpingo discs, Silver Rainbow Foil, Lessloss Blackbody, the Red X Pen and the Teleportation Tweak are probably not going mainstream any time soon.

PT Barnum once opined folks would be much better off generally speaking if they believed in too much rather than too little.

Ejr1953 wrote,

"Ions ago I had some really professional sales training, where they differentiated "need" from "sense of need"."

One assumes those were negative ions ago.