Larry Trask says:
"[A] quotation is set off by quotation marks and nothing else. A sentence containing a quotation is punctuated exactly like any other sentence apart from the addition of the quotation marks. You should not insert additional punctuation marks into the sentence merely to warn the reader that a quotation is coming up: that's what the quotation marks are for."
Here is the sentence with proper punctuation:
President Nixon declared "I am not a crook."
Adding more dots and squiggles to this perfectly clear sentence would do absolutely nothing to improve it. No punctuation mark should be used if it is not necessary.
Based on Trask's example, could we omit the comma after the dialog tags in the examples below - or should we always include them?
Joe said 'I hate dill pickles.'
Alex asked 'Where did she get that idea?'
Sam replied 'There's no point in going.'
Frank said 'I'm done with Debby. On Monday I'm filing for divorce.'