*Would you consider someone who cheated to win a contest the winner of the contest?
If someone cheated in a competition, he not tried to outsmart the rule, he also has taken the place of another person who merits the position he cheated to get.
*Can there be any kind of situation it's should be OK or acceptable to cheat to win? What kind of situation/situations?
In a situation where all the participants in a competition are cheats and are actively cheating, it will be stupid to still try to win the competition or contest with a normal approach. if you decide not to cheat in such a situation, it simply means you have decided to fail out from the contest, which sometimes is still acceptable from moral standards.