I remove ALL encoded links or code on themes.
http://www.motobit.com/util/base64-decoder-encoder.asp
I have no issues linking to designers, but refuse to include the footer links that are usually added after the fact.
Most of these themes with encoded footers can often be downloaded from the source without any encryption, just a link back to the designer.
An easy solution is to use paid premium themes, and not have to worry about it, plus get decent quality product.