Check out this video of this guy, Steve MRE from YouTube, eating a Hardtack cracker from 1863, which is most likely the oldest cracker ever eaten.
This cracker is 153 years old and did not taste good back then (or so we hear!), so it is safe to assume that it does not taste good now.
Hardtack is a thick cracker made from water, flour and salt. It is known to be very inexpensive and lasts a long time.