I agree Grendel, you are not safe from fakes or poor quality products anywhere but there are those that will knowingly sell you something thats rubbish and your much more likely to get that on Ebay. When its a life preservation device its not worth the risk, but for a 1.99 iphone lightening cable I might just take the risk, not the charging plugs however, fake ones of those can be just as lethal, and 240v lightbulbs.....
I would hope atleast that the trusted uk retailers are not deliberating selling items they know to be fake.
If its anything that could kill you, think very carefully where you buy it from.