When you scan to Formatted Text & Graphics
output, Acrobat analyzes bitmaps of text and substitutes words and
characters for those bitmap areas. If the ideal substitution is
uncertain, Acrobat marks the word as suspect. Suspects appear in the
PDF as the original bitmap of the word, but the text is included
on an invisible layer behind the bitmap of the word. This makes
the word searchable even though it is displayed as a bitmap. You
can accept these suspects as they are, or you can use the TouchUp
Text toolÂ

to
correct them.
Note: If you try to select text in a scanned PDF that
does not have OCR applied, or try to perform a Read Out Loud operation
on an image file, Acrobat asks if you want to run OCR. If you click
OK, the Recognize Text dialog box opens and you can select options,
which are described in detail under the previous topic.