Horrible? No they worked quite well, in fact so well that they caused the over priced Apples to lose share to the same systems made by others with lower cost parts.
What apple did was fail to make sure a profit came back to Apple from each clone sold, via that hard wired dongle I spoke of. That way only a true OS buyer could use it = Apple gets its profit.
Look at Microsoft, built on sales of the original OS and the descendants.
Apple is lucky it came out with the series of products it did. It is still a very small player in computers over-all, 2-3% share of that market, but it has 100% of the Apple market, but the X86 market has hundreds of players, most small, so the Apple stand alone % looks higher than many.
A good measure would be measure x86 sales from AMD and Intel and deduct the Apple portion.