Step by step solution:
In Adobe Acrobat 9 Pro (Not Acrobat Reader), from Menu "Advanced", select "Document Processing", then "Batch Processing".
From "Batch Sequences" dialogue, press "New Sequence.." button, enter a name for this sequence, eg. "Rotate CCW". Press "OK"
In "Edit Batch Sequence" dialogue, Press "Select Commands..." button.
In "Edit Sequence" dialogue, at the bottom of left column, select "Rotate Pages", then Press "Add>>" button.
"Rotate Pages" item appears in the right column. Click "+" beside it to expand all options.
Double click "Rotate Pages" item to get "Rotate Pages" setup dialogue then make changes if required. eg. you can select among "Counterclockwise 90 Degrees", "Clockwise 90 Degrees", or "180 Degress" for Direction. Press "OK" when complete the selection.
Back to "Edit Sequence" dialogue. Press "OK" to close it.
Back to "Edit Batch Sequence" dialogue, ensure the default option "Run commands on" is selected for the second item "Ask When Sequence is Run", and "Same folder as original" is selected for the third option "Select output location". Press "OK" to close the dialogue.
Now we back to "Batch Sequences" dialogue and "Rotate CCW" item appears in the list. Press "Run Sequence" button to run the new sequence.
"Run Sequence Confirmation" dialogue appears and item "Rotate Pages" is in the list. Press "OK".
"Select files to Process" dialogue appears. Now browse folders and select target files. Press "Select".
It goes back to "Batch Sequence" dialogue. If all processes complete, Press "Close". Otherwise repeat Step 8 to Step 11 to process files in other folders.
The "Rotate CCW" is saved in Acrobat as a sequence and appears in the "Batch Sequences" dialogue every time you run it. Next time if you want to rotate pdfs, just repeat Step 1, then Step 8 to Step 11 to process all files