https://lcb.wa.gov/mj2015/faq_i502_advertising

To file a complaint:  https://lcb.wa.gov/contact

May I have signs on the road with the business name that point to my parking lot?
No. Except for the use of billboards as authorized under RCW 69.50.369, licensed marijuana retailers may not display any outdoor signage other than two separate signs identifying the retail outlet by the licensee's business name or trade name, stating the location of the business, and identifying the nature of the business. Both signs must be affixed to a building or permanent structure and each sign is limited to sixteen hundred square inches.

May I have more than two signs if it doesn’t specifically say what I’m selling (i.e. just the name of my store on a billboard)?
No, not on the licensed premises; retailers are limited to two 1,600 square inch signs. However, you could just have the name of your store on an off-premises sign (billboard).  Text on billboards is limited to business or tradename, business location, and identifying the nature of the business. "Off-premises sign" means a sign relating, through its message and content, to a business activity, product, or service not available on the premises upon which the sign is erected.

Retailers are limited to two 1,600 square inch signs bearing their business/trade name. Does this include sandwich board signs that are used to advertise specials and events, often in the entrance of the property or on the sidewalk median?
Other forms of signage/outdoor advertising are prohibited, such as sign spinners, sandwich boards, inflatables, persons in costume, etc.