Wearing another clans Tartan?

[Downunder Kilt]

Hi Rabble,
I was wondering what the etiquette behind wearing another clans tartan in the form of a kilt.
It's something I know that would irritate me, but sometimes I stumble across a deal that is SO hard to pass up but it isn't always in Fraser or Patterson colors. It makes me feel guilty the idea of it, and I wanted to get the official scoop so I don't commit a kilt faux-pas
Seasaidh(Jess),

It would be rare indeed to find a kilt in Pat(t)erson tartan for two reasons:
1. There is no official tartan(as in recognised by a chief) because there is no Clan Chief.
2. There are unofficial Paterson tartans out there but they require a custom weave.

I have 2 of them
http://www.tartanregister.gov.uk/tar....aspx?ref=5094
and
http://www.tartanregister.gov.uk/tar....aspx?ref=3301