If a book is using cursing dfor shock value alone, it becomes rapidly apparent and I will put the book down.
Generally I find this to be indicative of a bad writer anyway, so not much of a loss.
If the profanity is used in a world-building way and accurately depicts the way characters would behave, I tend to ignore and gloss over it to the same degree I pretend people in real life didn't say anything... and not make a big deal of it.
Reviews are better than apps though!
