This point is easy miss and also skip the eye, for websites that you haven't used before or maybe are not in your list of bookmarked sites, it's good to check for spelling or graphic design errors, if there is any, then it's a scam website.
Or do they give fake giveaways, asking users to send bitcoins to receive more in return, scammers for sometime now are concentrating on starting fake giveaways, though some of this is easy to spot.