There is some demand for tailors, but not much.
1) clothes aren't mandatory
2) they're UL
3) they don't help you get better loot
4) most good clothes are high TT
5) most avatars don't invest in expensive clothes until they're committed to the game
All this means that once you pick your outfit, you tend to stick with it. Plus the basic clothes BPs are cheap and easy to get, so the people who really like clothes will just craft their own clothes most of the time.
In general, clothing is a real slow mover. Like Sam said, I make all of the Arkadian clothes on demand (including the Ark glasses). I used to try to sell clothes on auction but I rarely do that anymore, because there is low to zero demand sometimes and there are usually sellers who sell them for less than they cost to make, either because they can't calculate or they just don't care about losses. Some clothes can go for good MU, and you might have an advantage if you are a good colorer/texturer too.
We'll have to see what the avatar update does to the clothing market. According to Dave Dobson, the new avatars look much, much better, and that includes clothes. Apparently the clothes will have to be updated by each planet partner in order to take advantage of the new level of detail, and the Ark clothes are supposed to be ready when the update comes. If the clothes look amazing, it will probably stimulate the clothing market some. Though again, the same reasons above still apply; unless something changes it will never be a big market.