The Spot (also known as the Mark or the Sucker) is the player at a poker table who attracts much attention, largely due to his/her inexperience and lack of skill. The term is commonly used when good players are determining a good table to play at. There are a couple great spots at the $2/$5 game tonight! 
: a place where gambling is carried on or allowed as a business : a place kept as a gambling resort.