What would you do if you knew a former employer would write a glowing recommendation letter but you also knew his/her grammar and spelling were terrible?
Does the recommender know his/her grammar and spelling are terrible? Or is he/she one of these dumasses whom thinx he can rite good and braggs abowt it butt realey doesent no jakc crapp abowt basec elamentry speling and gramer that he shuld hav learnned inn kinergarden?
I would say this person leaves out a preposition, might use their for they're, uses the singular when the plural is required, etc. This person is very, very intelligent, but might put on two different shoes before going out because his/her mind is preoccupied with a solution to Laplace's equation. The details of grammar and spelling seem secondary the writing.