My fretless bass is an Alvarez, I certainly think it is Korean, or otherwise Pan-Asian, from wherever the factory must have been at the time, silk-screened Alvarez St. Louis, Missouri logo and all. I bought it through eBay and had it sent to my country, which took about a month. Seems like mine was originally intended to be fretless, and somehow found its way to be a fretless one. If it was made by the previous owner, he didn't said anything about it, and if it was some kind of factory work, it was pretty well done anyway. (Eventually I ended up swapping its pickups for a couple EMG 40J's, and it sounds pretty nice actually).
In the meantime, I had a gig - my Alvarez had not arrived yet, I played that with another bass - where I shared the stage with another group, and the bass player was playing an Alvarez (a six-er, with the same silk-screened logo as mine, BTW). I tried to make small talk with him, and commented I was having a Fretless Alvarez coming my way in a few days, and asked him about his experience with his Alvarez bass. My surprise came with his response: Well, I' ve been doing fine so far with it. I had Mr. Alvarez personally make this one for me...
Needless to say, no more words were exchanged after that.