AC polarisation. Does it matter?

Yes Polarity is very important. If incorrect it can effect the sonics of equipment. Hi-End manufactures check and make sure the primary polarity of the power transformer is correct. Check the archives for the proper method to check for proper AC plorarity.
Incorrect AC polarity can also can cause hum in a system connected by ICs.
On a safety matter the fusing inside the equipment would be on the other end of the power transformer primary winding. In other words instead of the fuse protection on the incoming hot conductor it would be connected on the neutral, the grounded conductor.

The AC polarity could also be off on the wall plug. No reason to believe the crew that installed the outlets in the house got all the wires put on the plugs the right way. They work very fast.

You can buy a polarity checker at most hardware stores. Well worth it for a small price.

Conrad Johnson use to put 2 prong AC plugs on some of their preamps, so you could flip the cord and desire which ways sounds best to you.

As most of my wires(Electraglides) are reversed except for the wires to the cdp and tuner should I reverse the polarity at the wall plug? That would reverse to proper polarisatiom the Hydra but then the amp and preamp would be reversed. The way I have it now the
plug from the wall is Reversed .The Electraglides in my system are all reversed in that the positive and neutral prongs switch at the iec. So I have a reversed cable to my Hydra with reversed cables from Hydra to amp and preamp which I imagine wouild be proper polarised as the hydra is switched and then it is switched back from the reversed cords from the hydra. The cords from the Hydra to my CDP and ny tuner are correctly wired so they would be reversed. What would be best for me to do. I could reverse the wall plug and the CDP and tuner would be correct but the amp and preamp would be reversed and vise versa.

(The AC polarity could also be off on the wall plug. No reason to believe the crew that installed the outlets in the house got all the wires put on the plugs the right way. They work very fast.)

They had better get the polarity correct or it can cause very severe problems with certain components. A cable box for instance will have 110 volts on it's coax center conductor if the recepticle is wired backwards.

I looked at your system and I don't think quality control is a problem with Shunyatas and Electraglides unless they make an export version with reverse polarity... I don't know.

Did you use a continuity tester to confirm this? Sorry if this seems painfully obvious, but the two ends match with respect to shape - flat on top and ground on bottom with the left/right terminals matching. Use a continuity tester on a prong/receptacle pair. If they are reversed, I certainly would not use them in my equipment.

For reasons stated above, reverse polarity is an issue and it's not minor. Usually, polarity is not an issue for pure resistive loads such as light bulbs.