yunger mann: Make sure you read the haskamos and not just look at the names.
Often the letter says that they haven’t read the book.
Sometimes the haskama is for a different sefer (e.g. The English Version of the Sefer Ma’alos Hatorah printed haskamos for the Hebrew Version written over 100 years ago!).
And every now and then you even get a haskama which says that the contents of the book is not Torah (still amazed the Mechaber has the chutzpa to print the haskama in his book when it says that)