I need a little advice from you guys. Have you ever had to clean a cassette tape? Just to be clear I am not talking about cleaning the cassette player itself.

The reason I am asking this is because I have a few pre-recorded cassettes from the 80s. The last time I used them was in the mid 90s. They have been sitting in a drawer most of their life and have been through humid and dusty environment. I had to wipe off the dust from the covers. Although the covers somewhat protected the cassettes I am sure some of the dust got through to the tape. I was wondering if I should clean them before trying to play them. 

Any thoughts or recommendations? Has anyone cleaned a cassette before? Is there a faster or better process or device than using pencil, q-tip, and rubbing alcohol?

Thank you.

Thank you deliverance