Sadly, words inside quote marks can have as many problems as the ones reporters create on their own. The problems often boil down to one question: Is the quote accurate?
But in dealing with dialectical spellings, that question becomes more nuanced. Reporters enjoy "writing how people talk," which means the occasional story reads like a vaudeville routine.
My employers (past and present) in the Tampa Bay area frown on expressions such as "gotta" or "gonna." That's good. Yet powerful pressures exist that make copy editors wary of changing quotes. That's good too. The desk shouldn't make everyone sound like William Safire.
But I've edited too many stories in which the writers valued quirkiness over clarity. Using substandard spellings, even on a limited basis, causes problems. Almost everyone says "gonna" or "gotta." That's the way we talk. We also pause a lot and say "um" and "er" and "well."
Most times, reporters don't reproduce such things. As sacrilegious as it sounds, I expect they often tweak what people say. Not to a great extent, and not harmfully. But they omit pauses. They take out the "ums." They pick and choose the phrases they use.
Thus, regionalisms should be suspect. Yes, that homeless man on the street may speak in a colorful manner. But if the reporter quotes him accurately in terms of syntax and content, what's gained by "gottas" and "gonnas" and "ol's"?
If an esteemed member of the city's elite grants that same reporter an interview, will the reporter then write a story containing all the idiosyncrasies of the source's speech? Probably not. Reporters don't quote George W. Bush as speaking about "new-ku-lar" weapons when he means nuclear ones.
There's a possibility of abuse. Reporters, under the guise of being descriptive, can perpetuate stereotypes. I doubt they would go so far as quoting some African-Americans as saying "axe" for "ask," though that's what the regionalism sounds like. But what's so different from using "axe" on one hand and "gonna" for a homeless man on the other?
Copy editors should challenge this. Quotes should be accurate but not discriminate based on class or race. If an important feature contains some abnormal spellings, has the protection of an assigning editor, and gains a dash of flavor from the dialect, leave the quotes alone. But otherwise, be watchful.
There are limits. "Ain't," for example, isn't a regional pronunciation for anything. It's a less-than-formal word. It would be dishonest to change such a word in a quote to "am not" or "is not." Twisting quoted grammar into more formal positions shouldn't be tolerated either.
Ultimately, it's not our job to make people look foolish by manipulating their speech. They have enough ways to look foolish already.