Jon, I am sure of my algae eater. If he were aggressive, sucked on my fish's slime coating, and were not effective at getting rid of algae, all of my fish would be dead long ago and algae would be all over my tank by now. If my fish are fine, if I never see him attack any of my fish, and if I have no algae in my tank - that means he has to be effective.
Now, I am not saying that "all" Chinese algae eaters are like this. I am well aware of their bad reputation. Mine may simply be an exception. It's not at all that I am some exceptionally good fish keeper. I am just like everybody else - I do what I have to do, i.e. regular water changes, etc. - which I wouldn't classify as somehow "exceptional" because these are the regular things we have to do.
I am sure mine is not Siamese. Here is what a Siamese looks like:
http://www.aquahobby.com/gallery/gsae.html. And here is what a Chinese looks like:
http://www.azgardens.com/images/Gold-Algae-Eater.gif. This is my algae eater:
http://putfile.com/pic.php?pic=1/2523175535.jpg&s=x4. As you can see for yourself, it is a Chinese form.
One again, all this is not to "prove" that they're good algae eaters - all I am saying that mine happens to be very good, it works well for me. I don't know what it is, but I have personally come to believe that these types of algae eaters will be aggressive if kept in small tanks, where they have no space to let their energy out. They're very lively and very fast, so they need a LOT of space. I'd say AT LEAST 30 gallons, not less. Of course tanks bigger than that would be great for them. Just imagine, how would you feel if you were confined within a tiny space where you could barely move? Fish feel the same way, and if they don't have enough space, they'll eventually become aggressive (in the case of a Chinese loach).
Considering that most people start the fish hobby as inexperienced beginners (as I have myself started; and when I was getting that alage eater, I didn't even know it had a reputation for being aggressive), they often fall prey to fish stores that just want to sell their stuff without, for example, informing their customers that Chinese algae eaters may be aggressive. I am not surprised that these loaches get a bad opinion if most of the people getting them don't even know what they're getting - and at the end, they're surprised and disappointed. But nobody even cares (or knows, as mentioned above) that they DO need a lot of space in order to be effective. I believe this is where the negative opinion comes from.