Lenses have personality !
For example, my Kiron 28mm f2, i wasn't fully happy of it when i bought it (was such a great deal i couldn't resist
), the colors don't "pop" like with my DA 40/2.8, the MF is turning the wrong side (comparing to Pentax one), the filter thread is damaged, so i could'nt use filter.
See ? A very bad start for this one.
But, the rendering is very special : it's like grainy at f2. Gives some impression of film somehow. it have some very special distorsion, not much visible, but just slighty present to give you the impression of difference compared to the day to day 18-55, DA40 or 55mm.
This lens is like a genius punkette : not very appealing but with secret charms
I call this personality : a very unique and lovely special thing, that make a lens be one of THE lenses.