I haven't purchased anything yet but I spoke with my title agent and some other investors and they all seem to it is a practical strategy. The main risk that everyone has told me is that the bank will foreclose sooner rather than later. I wish I was able to find someone who is actually doing it so I could get more detail on possible risks. In any case I expect to start with two or three purchases over the next few months and see how it goes before i plow too much into it. There is some information on one I did not intend buy here.
http://www.biggerpockets.com/forums/41/topics/71946-bought-hoa-lein-not-on-purpose
I have this one rented out and should have my investment back within a year from now. I haven't had any problems and the bank doesn't appear to be moving ahead with the foreclosure. I would never have paid that much for one on purpose. If I had got this condo in the $3,000 to $5,000 range I would have made a very nice return. Another thing to consider is buying HOA liens on houses because the fees will be much less and the rent higher and so earn a better return. You would be much more likely to have expensive repairs to make to get it rented out however.
I would love to hear anyone's experience with these, intentional or not.