If your scanned images consistently show streaks, lines, or smudges that weren't in the original, or if the scanned image has a general "dirty" appearance, a dirty scanning glass or ADF (Automatic Document Feeder) is a likely culprit.

Here's how to identify and address the issue:

Visual Inspection:

Look for dust, smudges, or debris on the scanner glass (the flat surface where you place documents for scanning) and the ADF glass (if your scanner has one). 

Scan Test:

Perform a test scan using a blank piece of paper or a document with a clean background. If the scan shows streaks, lines, or smudges, it's a strong indication of a dirty scanning glass or ADF. 

ADF Issues:

If the problem only appears when scanning through the ADF, the ADF glass or rollers are likely the issue. 

Check for Vertical Lines:

If the vertical lines appear in the same position on every scan, it's a strong indicator of a dirty ADF glass. 

Clean these areas shown below with isopropyl alcohol or a clean microfiber cloth with glass cleaner or even water will work.