The HOAs are protected because the debt runs with the land. While you can collect the past due assessments from the previous owner, you are liable for any assessments currently due. Whether or not you able to collect from the previous owner is always a challenge.
This does not mean you are completely without defenses. There is a new trend for HOAs to lump on all kinds of charges to run the bill up and many may or may not be legal. The problem is it could easily run way more to fight them.
You should pay them a reasonable fee ($75-$125) for an estoppel and demand an itemized accounting of all charges (no lump sum amounts). By law they have 15 days to provide this or you can file summary proceedings in court.
Demand any fines be documented with proof of notice that the owner was notified of a covenant violation and an independent fining committee met and voted to impose any fines. This is one of the most abused items.
There are no court cases on point, but I argue legal fees for the HOA as a named defendant in a mortgage foreclosure are the costs of doing business. No where in the Florida Statutes or the Rules of Civil Procedure do I find any authority for a defendant to pass on the costs of litigation to a co-defendant without a court order. HOA attorneys do this anyway. Because they are entitled to attorneys fees for the collection of past due assessments without a court action filed, they believe the statute gives them the right to pass on all attorneys fees without court action. I disagree!
Check if the HOA is allowed to charge late fees and what the maximum interest they are allowed to charge. This information is in their Declarations and Bylaws. Many overcharge!