"I wouldn't trust.....

.....him/her any further than I could spit". I am more likely to use the more familiar version of "...than I could throw him/her" myself [except I have thrown people, but only legitimately during my Judo years!]. This version derives from the hollowed out rods called spits used by the 19th century customs men. They prodded cargo to find out if there was smuggled goods concealed within.

There we go....always ready and willing with another recently gleaned fact to impart. I am a marvellous mine of useless information!

Arilx