Hey Jeff,
I prefer to use lighter fluid and a sharp razor blade to remove tape and tape residue. In the majority of cases the lighter fluid dissipates and does not leave any staining. However, you need to take care not to remove any paper, or as little paper as possible. Even after doing this for 20 years it can be a challenge.
As for tape stains themselves, scotch tape stains are typically permanent and need to be airbrushed out. When scotch tape ages the plastic simply falls off leaving a permanent stain so I simply resign myself to the fact that it will have to be airbrushed.
Old masking tape is a nightmare because it crystalizes and almost becomes part of the paper. In this case, if it doesn't lift using lighter fluid, I carefully sand it off, but this is very time consuming.
My favorite is butcher tape which simply falls off during the linen backing process.
We just finished linen backing a three sheet which had masking tape along every fold line on the back. It took two of us 90 minutes to remove. It was a monumental task.
Let me know if I can ever provide assistance.
Cheers, Dan Miles, Backingtothefuture.