I hate to speak before all the facts are in but it kind of appears that you are the only one confused by the symbol that looks pretty much like an arrow. What makes matters worse for your position is that the HiFi Tuning fuses actually sound considerably better when the arrow thingie is pointed in the right direction. At least that’s what people who have actually heard the HiFi Tuning fuses say. Furthermore Isoclean has actual, you know, arrows that should not be so darn confusing on their fuses. Have for twenty years. The test data sheets on the HiFi Tuning web site are actually from an independent testing facility. Hel-loo! As it turns out you have apparently bought into the old wives take that fuses are not directional.
Well, the facts **are** in. The symbol to which I refer is a stylized diode symbol (its not an arrow; that one was good for some laughs around here) bypassed by a capacitor. However it is really a stylization which is why I used the word 'logo'. Measurements of the fuse show no diode characteristics (and as Thom just pointed out as I did a couple of pages earlier, if it did have such effect, it would fail quite quickly in an AC application) nor any capacitive effects. Further, if there was a diode effect, in one direction it might not work at all.
Disassembly of the fuse shows it to be constructed in a way similar if not identical to other commercially available fuses (a ceramic tube with a lightweight wire fuse element within; FWIW the wire appears to be damped by a lightweight insulation, presumably to limit or damp the motion that otherwise can be observed in many fuses when current is applied. Its likely that this insulation is the primary improvement, more important than the plated ends.
These fuses were originally imported by a customer of ours, who sent samples to us. He never at any time indicated anything about them being directional. The directional aspect is clearly a made-up story not supported by fact or for that matter, the past or current importer. It is supported only by expectation bias; anyone who really wants to get to the bottom of it will find that if they try reversing the fuse again after finding the 'favorable' direction, will find a similar benefit in the other direction. That is if they keep an open mind.
Any supposition that the fuse is directional is mistaken, any commercial entity that attempts to convince others that this is so is engaging in fantasy.
If a fuse really were directional, it would have inherently inferior properties compared to a non-directional fuse.
And again, our customers do report positive results using this and similar fuses. About this they are quite adamant! None of them have reported any directional characteristics, and since the inception of this thread, several have made a point to us that auditioning them in either direction has had a null result.
