Never Buy a Self-Published Book at a Car/Craft Show

I have never written a book so I find it hard to criticize someone who has the determination and concentration to do so and then go on to publish it. On the other hand, I just read a slight paperback that I bought at a car/craft show that had a clever  idea for a series (there are several titles) but turned out to be the definition of bland, amateur, and trite. What bothered me most from the very beginning was the shifting of voice and tense. Since it was a short book, I soldiered through until the end. The plot was nothing special. The sentences were short and choppy. (Did I mention the author had been a teacher?) Maybe I SHOULD write a book.