Similar to JJohnson (#10) : I know some of my guns are not 100 % reliable , although I do shoot them once in a while (I call them semi-safe queens).
As for absolutely trustworthy : any of my S&W DA revolvers, (J, K, L or N frame) from .38 Sp on up, or one of my 9 mm : FN HP, CZ 75 B or SIG P-210.