always a good idea if you want to have a default judgement issued against you.
Thats only if they send a summons and you dont show. I highly doubt they will sue you for using their likeness if the banners which are on your website are being automatically rotated from various casinos / sportsbooks. They are sueing the wrong company. They need to go after the people who are infridging. For example, If I own a billboard company and someone leases the billboard. They send me the poster and its a copyright infridgement? Sueing the Billboard company is moot. They need to go after the company which designed and displayed the likeness. Not person who owns the mechanism for display. They have no bering on the graphic design.