"The Sign of Four": An unmitigated pile of literary sh*t, never so glad to finish a book ever. Only finished it out of some perverse desire not to let the book beat me by giving up on it. It is truly a book not be dismissed lightly but with a bloody big throw over a cliff.
Tom Clancy: the books were strangely readable but as the series progressed they became just a load of propaganda for how great America and the American military is and in pushing his own political ideology they became just tiresome. In fact the last one Red Rabbit is nearly as bad as The Sign of Four. In Clancy's world first come Americans, then the British a bit behind then come the rest of the world in a descending order of the usual suspects.
The Sean Dillon series by Jack Higgins: its appears to be written by a computer, largely the same plot, the same characters(even if the names change) and locations, even some of the dialogue. But they are still extremely readable and pass an entertaining few hours without engaging the brain.
Ken Follett's medieval doorstops “The Pillars of the Earth” and “World without End”: B-movies in book form. Execrable writing. Clearly Follett has mastered the dark arts of sorcery. What other reason is there for why I couldn't put them down?
Anything by the late Colin Forbes: generally containing too much repetition of 'as you know, XYZ protagonist is an expert something or other that is vital to this mission', and featuring the worst fashion cues in contemporary pulp literature, with a heroine whose style guru seems to have been Margaret Thatcher. Nonetheless I seem to have read book after book of his from the library in hopes that, on the basis of the professed book a year, there surely had to be some improvement as time passed. I was wrong. He was truly the Barbara Cartland of spy fiction.
I also succumb to Lee Child's Reacher series: "Blue Moon" just came out and I duly read it. Of course it's formulaic, but it's great for a rainy afternoon indoors (still sunshine where I live and temperatures above 25 C), snuggled into a large armchair in the garden looking at the pool and accompanied by steaming mugs of tea and gluten-free beer cake. Possibly not the image Mr. Child had in mind, but I don't just drop cake crumbs over any book, you know.