Second guy: Really? I find her highly scrutable.
Wait, you say. Isn’t that the same old joke you used with ineffable? Yeah, basically.
Here’s another lonely negative. There’s inscrutable, meaning ‘That cannot be searched into or found out by searching; impenetrable or unfathomable to investigation; quite unintelligible, entirely mysterious.’ But you don’t run across scrutable. Inscrutable, which appears as early as 1450, comes from late Latin inscrūtābilis < in- (neg.) + scrūtārī, -āre, ‘to search or examine thoroughly, to explore -able suffix.’
According to the OED scrūtārī comes from scrūta plural, ‘old or broken stuff, trash, frippery, trumpery’; the etymological sense of the vb. is supposed to be ‘to search even to the rags.’
Scrutable, meaning ‘something that can be understood by scrutiny,’ has been used occasionally in English, but mostly in opposition to inscrutable.