As far as more subtle clues go, people will complain about the pack having nothing good when its full of good cards in two or three colors, allowing you to deduce their guilds
You can't pay more to get more than
Other cards can automatically attach equipment to target creatures , which gets around paying for the equip cost, [c]Armored Skyhunter[/c] and [c]Ardenn, Intrepid Archaeologist[/c] are all examples of these cards
The Counter Intelligence deck has a Jeskai identity and is focused on putting counters on Artifacts and generating tons of value when you do
In fact, his Commander deck was the "Deck of the Day" over at Wizards of the Coast
Each color has different spells and creatures affiliated with it, but also interestingly, each follows a different philosophy, which I personally find to be one of the most intriguing aspects of Magic: the Gathering