Bluebottle diagram focused on the UCDs. Models predict that early Y dwarfs are located in a horizontal band below the main bluebottle body. While there are many photometric candidates found there, none of them have been spectroscopically confirmed. We manually inspected the available spectra of the objects below the black line and found that most of them are not consistent with UCDs (black crosses). Apart from the T dwarfs, only seven other objects show UCD (or stellar) spectra.