I hate to be the bearer of bad news...

...But I believe that there is no evidence to suggest that "The Funhouse of Dr. Freek" was ever released. Back in July 2017, I spent a lot of time looking for this book. At that time, I was one of the only people searching for it. It's possible that "The Funhouse of Dr. Freek" may have been written, or — at the very least — exists in the form of outlines. However, this article should be reworded so that it doesn't lead people to think it was published. We can still mention the reviews, but they shouldn't be taken too seriously.

Each GoFS book teases the next issue in the last couple pages. Book 35 does not mention book 36 — at least in the copy that I saw. Adding to the case that this book wasn't released, there are two Fear Street Sagas books that definitely went unpublished around the same time: The Raven Woman and Carousel of Fear.

Edit: I updated the article appropriately, and I added some useful information about the Monster Dog contest. / Edit 2: I found some old publications mentioning the book! Now I know where the title came from.