I think of clones more like replicas. In the end, someone is still COPYING an original item. A lot of manufacturers take a harsh stance to the cloning of their products, because a clone is essentially a pirated copy of an original. Not all clones are built to the same specifications and standards as the original, which is what's known as a 1:1 clone. Some clones, however, look like 1:1 matches, but they tend to have small differences, like being made of cheaper materials, or having different material connectors, stuff like that.
Some clones have the logos and identifying marks erased/replaced. These are either complete forgeries, or simply items branded for resale by other companies.
I prefer authentics, it can be hard to get authentics in places where ecigs are banned, but I still disagree with the practice of cloning. It really is no different from bootlegging. The products are typically sold as authentic looking clones, the clomer gets all the profit, while the company that came up with the original product gets nothing.
I've got nothing against people who own clones, most b&ms wouldn't be in business without cheap clones to buy wholesale, but I still think the cloning of products isn't right and, in some cases, could be dangerous.
Then of course there's the rare occasion when a clone is better than the original. I don't have any examples, but I've heard of it before.
And of course, the only time I really think cloning is excusable, is if the original product line was discontinued yet people still want that product. In that case, clones are the only option.