@Ron J. we see this all the time. In short, it varies by county. The purpose of these fines is to punish rogue landowners and encourage good behavior.
In theory you can sell the land with the liens attached. You will get almost nothing for it because most people don't know that the problem can be solved pretty easily.
In many counties its simple to get the fines removed. Even Cook Co IL (a notoriously tough place to business) will forgive the fines if the new owner has a plan to fix the property and solve the problems which are usually public safety related.
Here is what we do:
1. Find a local realtor to appraise the land - maybe its worth $7,000 or $70,000 or $0. I have seen BPO's all over the map. Assuming its worth $7,000....
2. Find a local lawyer who deals in building court matters. Explain the story and get them provide a fixed fee to remove the liens. They will tell you if its possible. Shouldn't be more than 1 hour of court time so $500 total.
3. You will need to fix the problems on the land (garbage, grass longer than 8 inches, etc). If you have the time and interest, you could get outline plans for a home drawn up (only after you are sure you can get the liens released).
4. Get the liens removed - usually takes a month or so in total.
5. List the land with clean title
That will get you the best possible price. The key piece of the puzzle is figuring out if the land is worth anything and if the liens can be removed.
Good luck. Let us know how you get on