Are you talking about the RR database or just in general?
For the county database pages right below the county map there is a dropdown list:
Input Frequencies: Hidden
Change it to
Shown.
Input frequencies are not always listed unless somebody submits them. Input frequencies for trunked systems are not show in the db at all. You have to look at the license data for those.
Some bands have standard offsets so it is easy to tell.
wiki.radioreference.com