I bought a fake Computron on eBay once, unknowingly. It was OK, I was happy to experience the mold as I'd never seen it in real life but the quality of the parts was dissapointing, a lot of mold flash and the plastic was of an inferior quality to other toys from the line around that time. Transformation and combining is a bit janky as a result.
I have since decided that I don't really like it and if the opportunity to get a legit computron came up at a reasonable price I'd certainly think about it.
The same thing happened with a G1 Devastator but it was undersized and when I questioned the seller I got a partial refund. It had similar problems and I recently bought the Animated face G1 reissue and I am very happy with that.
Like has been said it's generally frowned upon due to the potential for someone to be fooled into thinking its the real deal but if you purchase knowingly so you can experience a mold for yourself then it's your money.
I am unaware of a KO G1 toy that matches the original in quality, so you are likely to be a little dissapointed by that factory when if you purchase the real deal, probably not, except for any developed play wear over time.
It is this sort of discussion that highlights how much potential there is for further developement of Generation 1 reissues. I wonder who's next. perhaps the aerial bots or maybe the protectobots. ..