Over the past fifteen years of running photography workshops one of the most frequent equipment issues that my clients suffer from is malfunctioning remote releases. It quickly became apparent that it was almost exclusively the aftermarket brands that were effected, particularly those originating from China. The most common problem is that they can cause the camera to lock up - the solution to this is normally to remove the remote release and all will be fine. However, on occasion attaching the remote release in the first place has shorted the electronics and caused more terminal issues. On several occasions this has required expensive repairs at a Canon service centre to get the camera body working again.
My advice to clients is always to buy the genuine Canon or Nikon (although they tend to be less affected) remote releases. Unfortunately these are very expensive for what they are. My solution is to buy used ones on eBay where, for some reason, there always seems to be a constant supply! I tend to buy several at a time so that I always have spares (I'm often dangling them in rock pools and the like!). The RRP for a Canon RS-80N3 remote is £60 (although you can buy them new for around £40). I recently bought three in excellent condition on eBay for a total of £19! It's really not worth the risk of buying the Chinese copies when you can get the genuine article for this sort of money.