I am horrible
at remembering people. Hardly it passes a day without someone smiling, waving, or greeting me, and I have absolutely
no idea who they are. I have learned to live with it, and how to avoid making a fool of myself (well, mostly), but sometimes it can be quite embarrassing.
I must admit I rarely pay attention to people, so in the end it's just a mass of indistinct humanity to me.
Also, my less than perfect and highly idiosyncratic command of English is not outside the purview of dumbness, as I've been using the language for a whole bunch of years now. Not being a native speaker might cut me so slack, tho.