If your ball is in an abnormal ground condition, for example a rabbit scrape, what is “clearly unreasonable” (under the exception to Rule 25-2) when it comes to being able to make a stroke?

Would the ball need to be “totally unplayable” (like in a blackberry patch or under a thick tree)? Or would a stroke, say, using your putter with a restricted 10cm backswing, still be “reasonable”? If not, what would be?

I am aware of the Exception using the words “without an excessively abnormal stance, swing or direction of play”. I am asking for opinions about whether a player who has got a normal shot, no matter how restricted, is always entitled to relief.

The purpose of the Exception to each of these Rules (24-2b / 25-1b) is to prevent the player from fortuitously obtaining free relief when it is clearly unreasonable for him to play a stroke because of interference by something from which free relief is not available. (D. 24-2b/19).
It is always a call based on the circumstances. Interference occurs when the object/condition interferes with the players stance or area of intended swing. It doesn’t state that the intended swing has to be full or whatever. For me, if a player sought relief and indicated the type of stoke and direction of play that he intended to play, and it was possible, I would probably not object. IMO it is impossible to write a hard and fast answer, the competence of the player in question could also be a factor to consider.