Here in the standard LDS and RLDS texts, there is a comma after teachers, which implies that all teachers sell themselves “for that which will canker”. The relative clause should be restrictive. The 1906 LDS edition removed the comma. The same should be adopted in the current text.
A similar example is found earlier in the text where all the printed editions have a comma after the rich:
For further discussion of this example, see under 2 Nephi 28:15.
Summary: Remove the comma before the restrictive relative clause in Mormon 8:38; the text is not condemning all teachers, only those that sell themselves “for that which will canker”.