If they smell good and not cheesy they're fine. They've degraded, and you should figure out how much alpha acids are left.
Check out the following formula:
future alpha = A*1/e(k*TF*SF*Days)
where e is the base of the natural logarithm. In Excel and other spreadsheet programs, e(n) is expressed as EXP(n). Let's walk through an example. Let's say we bought some Cascade hops at 6.4% a-acid 1 month ago and we want to brew with it 1 week from today. We're storing it in our home freezer, which is ~10 degrees F, in its original nitrogen-flushed oxygen barrier packaging. Table I shows that Cascade's percent lost value is 50%. Table II reveals that a percent lost of 50% gives the value for k as 0.00385. Table III shows that the corresponding value for TF is 0.228, and Table IV shows that the value for SF is 0.5. We bought the hops 30 days ago, and adding the 7 days from now, the value for Days becomes 37.
So our formula now looks like this:
future alpha = 6.4*1/e(0.00385*0.228*0.5*37)
which gives us 6.3% (rounded), which really isn't all that much different but proves that good storage conditions can really make a difference in a poor-storing hop like Cascade. If we stored it at room temperature in a poly bag the numbers would look like this:
future alpha = 6.4*1/e(0.00385*1*1*37)
which equals 5.6% alpha - a much more significant difference. It also shows the effect of poor storage conditions.
You can get the tables at
http://morebeer.com/brewingtechniques/library/backissues/issue2.1/garetz.html
