Spellcheck only "real" copy.
Add an option in "Check Spelling" to tell it to "ignore automatically generated placeholder text". So that Spellcheck would flag only real copy. I often use both in my documents and it's hard to check a 40-pg document when it keeps stopping at several paragraphs of placeholder text.
It would be nice to have the option to not spell check Master pages. As you can do in Find.
No need for (further) software support. Just set the language of your placeholder text to [No Language].