Some times when I'm replacing a whole string of text the color or some other attribute changes. Example:
1. on my page is a paragraph of text that needs to change.
2. I copy new raw text from a Word doc (so it has no formatting associated with it)
3. Paste it over said paragraph of text in InDesign
4. New text picks up font characteristics but the color is now different.
There is no hidden character at the beginning that could be causing this, so where is InDesign getting the color attribute from?
Try using Edit>Paste without Formatting (or, if you use the keyboard shortcut Command V to paste, just use Shift Command V instead).
Use Paragraph Styles and Character Styles. After inseting the text apply the correct style.
And you can do as Migintosh wrote. But I strongly recommend never to work without styles.
Even if you work with styles (as I do), you can paste text into something styled, and it won't necessarily adopt the style applied at the insertion point, but Paste without Formatting will allow you to have the new text adopt the style without local overrides.