Ok. so here is the scene.
I started via live another life, getting off the boat in Solitude. took Lisette as a follower ( my mod).
I have Dova's angels mod for Uthgerd; I subsequently made my own based on the face supplied with Dova's angels for Uthgerd. I set default clothing as farm clothes, like I do for all my mods (except my Lisette mod which I leave with vanilla settings). Bandits in the area were kicking our butt, so I bought a horse and travelled to Whiterun for reinforcements. I take Uthgerd (my mod) and take her plate, and give her studded armour, as that is what my crew wears. Sold her plate.
After several escapades (and my creating two new followers, a spell sword, Arwen, and archer Annika, I cut Uthgerd loose after we all make it back to Solitude and join back up with Lisette ( I have a multi- follower mod, EFF).
Uthgerd travels back to Whiterun and hangs out in the Bannered Mare (her usual AI).

Next time I visit the Bannered Mare, Uthgerd is clothed in nothing but her two-handed steel sword!! I didn't take her studded armour and she should default to farm clothes, if anything.

If I tell her to follow me, and step outside the tavern, she will be wearing the studded I equiped her with.
Back in the Mare, she is Bare!!
I have equip itemed her via console and she takes the additional armor and wears it.... until I exit the Mare, wait a day and come back. then she's in the alltogether again!
I've also tried disable / enable; resurrect, and when she's buck nekkid, she stays buck nekkid.

Kind of an immersion killer for everyone to go around and not notice the naked warrior in the room.

Any ideas of how to get her outfit fixed? It only seems to be "nothing" when she is in the Mare. Anywhere else she is dressed properly.
Problem is, unless she is following, she doesn't leave the BAnnered Mare.

I tried resteinventory as some suggested in a different thread in the CK forum (similar topic).
It didn't work, as far as making her wear something.
I equipitem - ed her with studded armour, hide boots and hide bracers. I followed the item code with a 1, equipitem 0001b398 1
She wore the items, but only the boots persisted after I left the interior and returned.
I then re equipitem - ed her with studded armour, hide boots and hide bracers. This time I followed the item code with a 0, equipitem 0001b398 0
The "0" was suggested by elderscrolls wikia, as a 1 sometimes makes some items unequipable.
This worked for the studded armor and hide boots, but not the bracers.
I used codes:
Studded armor: 0001b3a2
Hide Boots: 00013910
Hide Bracers: 00013912

I did a showinventory and got:
1 - Lockpick (00000000A)
1 - Silver Garnet Ring (000877AB) (100, 100.00%) - Worn
--->BAD EDITOR ID (0008E841)
1 - Flawless Garnet (00068521)
1 - Tomato (00064B42
1 - Hide Boots (00013910) (100, 100.00%) - Worn
--->BAD EDITOR ID (0001B395)
1 - Studded Armor (0001B3A2) (100, 100.00%) - Worn
--->BAD EDITOR ID (0001B398)
1 - Hide Bracers (00013912) (100, 100.00%) - Worn
--->BAD EDITOR ID (0001B39B)
--->BAD EDITOR ID (00103874)
--->BAD EDITOR ID (00103875)

Anyone able to tell me what the significance of the "BAD Editor ID" lines mean?
Why are the ID codes different than the item I equiped her with?
Why are these showing on the wearables, but not the non-wearables?

I will check if these items persist after leaving on a quest and returning in a game day.

I went into the CK, and checked her inventory. I think part of the problem was that although her default was farm clothes, there was an armor set (green square) for studded armor in her inventory list that might have been causing a conflict with the similar items i equipped her with.
I deleted that set and saved.
When I equipitem 'ed her in the console with the studded armor, I appended a 1 after the item.
Left the Bannered Mare, went on an expedition.
Came back and she is still wearing the studded armor.
Will see how the 3, 5 and 30 day cell reset goes.
Hopefully this is problem-solved.