https://help.libreoffice.org/Calc/Logical_Functions#AND needs to mention that 0 and '' (empty string) is also considered as a FALSE statement. Very likely these has to be mentioned at other logical functions
NEW.
I think the functions AND/OR behave like that: 0 is FALSE, all other numbers are TRUE. Empty cells and text in cells are ignored. If all arguments are ignored or there are no arguments, there is an error. Text as a direct argument (not in a cell) leads to an error. Errors as argument lead to an error.
@gilward: yes. Will add add it to the documentation, please?
Olivier Hallot committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/help/commit/?id=781da1e8175459f27cca84bed2ca209b3e030067 tdf#99611 improve function AND() documentation