I have bought 3-4 from ebay the one that has arrived looks like this:
I have already installed the library and the GFX library. I then compiled and ran the example program they give with the library but no fish.
My OLED is at address 0x3C as I discovered by using a scanner sketch.
The adafruit library was using a different address so nothing was working. The OLED is working now.
Except there are two colours on it: a band at the top, maybe 10-16 pixels, which is yellow. Then a black line, it's always black. Then the rest which is cyan.
The example program displays a lot of graphics and it does not matter what it is, the top 8-16 pixels are always yellow and the rest are cyan, with a black line in between.
Edit: looking at the pictures of similar items on ebay it would appear this two colour scheme is done on purpose for mobile phones, at the top you have signal and battery indicators - maybe.