If the tape is something like 456, it doesn't matter if it's never been used. When I refer to new tapes, I mean freshly manufactured (only RMGI or ATR Magnetics).
The tapes that are prone to sticky shed can be still sealed in their boxes and even if they've been carefully stored, they can have problems straight out of the box.
The tape brands/types to look out for are listed in a table on post #24 of the Beginners Guide.