These people are paid to stand alongside the road (and sometimes in it) to hold large signs (and usually to wave or spin them). This is often the practice when a store is going out of business (usually a furniture store). In fact, many times when a large store is going out of business, they sell the whole thing to a "liquidator", who then does the "going-out-of-business" sale. The state has specific laws regarding these sales, largely intended to prevent the liquidator from bringing in lots of other cheap junk and selling it at a tremendous "savings" or for a store to have repeated "going-out-of-business" sales.
While laws restrict the placing of advertising signs, some courts have decreed that a person holding a sign is protected under the 1st Amendment. Of course, we all know that the 1st Amendment was intended to protect one's own opinion and allow it to be "expressed". Being paid to hold an advertising sign has nothing to do with this.
However, Baltimore County appropriately has specific laws related to this type of activity in roadways and public property. Section 18-2-607 of the County Code says "a person may not stand in a roadway to sell or attempt to sell any goods, wares, or merchandise of any description to, to solicit or accept any donation from, or to distribute printed material of any description to any occupant of any vehicle. The question always comes down to "what does roadway mean?" The County Code refers to the definition in Title 11 of the Transportation Article of the MD "Annotated" Code, which does not exist online anymore. The "unannotated" code, which is online, says "Roadway" means that part of a highway that is improved, designed, or ordinarily used for vehicular travel, other than the shoulder.
Many of the people holding signs are standing in traffic islands at intersections, which surely must be prohibited due to the danger they present. Perhaps the County Code needs to be enhanced.
This one is for a furniture store that had a sale every weekend and had been putting up hundreds of "snipe" signs each time. After I got them dragged into several Code Enforcement hearings and fined, they started using these people. It was apparent that they were using a company out of Pennsylvania, both to place the signs by the roadside, and to provide these people. They also provided "mobile" ads.