Dear Miss Snark:
A friend of mine who published a non-fiction book to some critical acclaim in the early 1970s agreed to read my manuscript (fiction) to double-check me on events and locale. His non-fiction book touches on the timeline and the setting in which my novel takes place. He is the only person to have read my work. In his critique I thought he used several phrases which nicely portray the book. They are more insightful than just slobbering praise.
Question: Should I dare use his observations in my query to agents? The last book he published was thirty years ago, so, obviously, he's not a household name in publishing circles. I want to use the quotes because they so well capture the book, but my Snark-conscious is telling me to forget about it. What say ye?
Normally, I'd say leave out all the beta reader comments, even the non slobbering ones. However, if you have NO other publishing credentials, you can include something like "When Mr. X (best known title: publisher) was helpfully vetting my book for anachronisms, I was pleased he said it was 'non slobbery'".
This gives the correct context for the quote so it doesn't look like it's your bookie saying nice things so you'll make some more dough to play the ponies.