Hello and thank you for the opportunity to assist you. My name is ***** ***** I will do my very best to answer your legal questions.
No, it's not terribly difficult to evict. It's as simple as filing the eviction forms, serving the occupants, and at the hearing you show the judge your deed. The former owners don't generally have a viable counterargument.
Having said that, it's risky to buy property like that (which is one reason it can be a great deal). The risk is that the former owners could be emotionally unstable after the foreclosure. I've certainly seen enough situations where former owners literally destroy a house after a foreclosure.
If I were going to buy a house under these circumstances, I would offer cash for keys, and just accept it as the cost of doing business. In other words, offer them cash (e.g., $5000) for moving expenses. The caveat is that you can condition the payment on (1) they vacate by a certain date, and (2) they leave the house in broom swept condition and cause no damage. Under those circumstances, you can likely avoid an eviction, and also avoid the risk of damage.
Does that answer your question? Please let me know if you need clarification, as I am happy to continue helping you until you are satisfied. Also, please remember to provide a positive rating via the stars (and note that your positive rating is the only way that I'll get credit for helping you, so it is much appreciated!). Thank you. :)