Official Rules are the most-scrolled-past document in commerce. They are also the only place a promotion is legally obliged to tell you the truth in detail, which makes ignoring them a slightly odd habit.
The good news is that they are formulaic. Once you know the ten or so sentences that carry weight, you can read any set in about ninety seconds and know more about the promotion than almost anyone else playing it — including, sometimes, whether it is worth entering at all.
Here is the field guide, one clause at a time.
10 entries, one per page.