I saw that 1 BTC was allocated as the main prize of the contest, but I do not know how honestly the results are summarized and indeed this bitcoin is transferred to the winner. It is more realistic to get a Bitcoin particle through a faucet, but this is too small a part, which is measured in cents.
If the contest creator is reputable and have proof that they really distribute the prize to the real winner and transparent for everything peoples ask then maybe its worth to try to participate on those contest...
Of course, if a well-known brand acts as the organizer or sponsor of the event, then there is no doubt about the honesty of the winner's choice. But we most often see that such an organizer is an unknown company that does not even have its own website, so you should not expect an honest distribution of the prize fund.
For having that we can assure that they really sure to distribute the prize to the real winner, since this can give good exposure to their brands and can give more bigger impact since many people will talk about the happenings of the event especially the prize given by the sponsor of the event.
Only those unknown website those unknown website is really valid to doubt because we don't know if they are real with their contest, as well if they could really give the prize without further more requirements asked.