Why does my ScanSnap fail to recognize some text?

ScanSnap may occasionally experience difficulties recognizing (OCR) the following types of text:

• Outlined characters / fonts
  Outlined characters cannot be recognized. Input the text manually using the keyboard.
• A phone number which is printed on the same line as the address or E-mail address.
  A phone number printed on the same line as the address or E-mail address is will not be recognized. Input the telephone number manually using the keyboard.

Target ScanSnap:
SV600 / iX500 / iX100 / S1100i / S1100 / S1300i / S1300 / S1500 / S300 / S510 / S500 / fi-5110EOX2 / fi-5110EOX