In English writing, there are certain conventions for representing foreign accents. For example, a French character could replace all of zeir TH's wiz Z's, while an Italian might-a add-a short-a vowels to all-a their words, a German vould svap V's vith W's, ja? and a Japanese might assimirate their riquids.
In other words—exaggerating certain stereotypical features, as a cue to the reader to fill in the rest. When I see Z's replacing TH's in words, I also imagine the uvular "r", nasal vowels, and ultima stress of a thick French accent, even though the author didn't mention those.
Does anything similar appear in Latin literature? Is there some particular type of error that authors would use to indicate a foreign accent?
NB: I'm looking for spelling or grammar variation used intentionally by the authors, and specifically to suggest foreign-ness or non-native speech.