Airbnb is an immensely popular platform for providing peer-to-peer lodging opportunities. According to its web site, the company, which was founded in 2008, has arranged lodging for more than 40 million travelers to date. It claims more than 1.5 million listings in 34,000 cities spread over 190+ countries. But it is not popular with everyone. In jurisdictions all around the country (primarily cities and vacation destinations) it has been subjected to a variety of criticisms and complaints. Many of these have resulted in the adoption of new ordinances and/or renewed zeal in the enforcement of existing ones.

Here, without taking sides, we review a number of the issues that are frequently raised. They fall into three somewhat imprecise categories: (1) code compliance, (2) social impacts, and (3) contractual obligations. (Also, we note that Airbnb is not the only business operating in this space. But it is certainly the biggest gorilla. Hence we speak here only of that company.)

(1) Codes and ordinances affecting Airbnb lodging arrangements vary greatly among cities and counties. Many prohibit residential rentals of less than thirty days in any area other than those zoned for hotel or motel use. Others may allow short-term rentals, but require a fee based on actual usage (e.g. a "transient occupancy tax"). In other jurisdictions where residential rentals of less than thirty days are allowed, there may not be an occupancy tax, but there will be a registration requirement -- along with a fee. Needless to say, more than a few Airbnb hosts have failed to comply with such requirements. Our local Orange County [California] Register conducted a survey that showed there were literally hundreds of local Airbnb listings in cities where such rentals were prohibited.

(2) What I have classified as the "social impacts" of Airbnb take place at different levels, the most local of which being the neighborhood in which the listing exists. Neighbors in close proximity, such as in a condominium development, frequently complain of increased, louder than usual, and often late-hour noise. None of this might be surprising -- though still annoying -- in a vacation area motel, but it is not what most have signed up for when they purchased their condominium as a permanent residence. The most notorious offenses seem to be in the cases where the host has provided an entire free-standing home. If it's next to a theme park, or close to a popular beach, both the numbers and the manners of the visiting guests can easily get out of hand.

On a much broader social scale, serious concerns have been voiced about the fact that the full utilization of homes and apartments for short-term and vacation rentals has the effect of reducing the available rental housing stock in areas where shortages already exist. Santa Monica and San Francisco are cities where this has been a particular concern. An excellent in-depth report done by the San Francisco Chronicle in July of this year asserted that at least 350 entire homes were listed as available vacation rentals throughout the year. The Chronicle framed the debate in this way:

"Opponents say short-term rentals are so lucrative that greedy landlords and tenants illegally divert precious housing stock to the practice. Proponents say services like Airbnb help regular people afford to stay in San Francisco, while forging international friendships."

Another social issue in connection with short-term and vacation rentals is the potential for Fair Housing violations. Hosts have a great deal of freedom in selecting and rejecting applicants; and they are far from being subject to the scrutiny of regulators who have been policing the standard rental markets for years.

Finally, there is a fairness issue that is raised, naturally, by the standard commercial competitors of those who would provide short-term rentals on a peer-to-peer basis. It sounds much like the battle between commercial taxi operators and the Uber operation. Hotels and motels, like the owners of cabs and cab companies, say that it is unfair for these "free lance" competitors not to have to be subject to the same health and safety safeguards and standards that they must meet.

(3) Under the category of contractual obligations Airbnb hosts need to be aware not only of municipal ordinances, but also the CC&Rs which apply both in condominium developments and many communities of single-family homes. It is quite common for those documents to prohibit rentals of less than thirty days, and sometimes even longer periods.

Finally, it is common for Airbnb hosts to be offering out an extra room, or even a roll-out bed, in an apartment which the host is renting. Indeed, it is by earning extra income in this way that some tenants are able to keep up with the steep rise in rental rates throughout the country. The problem is that it is often the case that the tenant/host has a lease agreement with the landlord that prohibits sub-letting in this manner.

The remarkable success of Airbnb, now with a valuation in the neighborhood of $20 billion, demonstrates its popularity and the fact that it is meeting certain consumer needs (or wants) in the same way that Uber has. But it is also a business model that has its share of potential problems. REALTORS^®can expect that they will be drawn more and more into the land use and property rights issues that surround this business. They will do well to be acquainted with the issues.

Bob Hunt is a director of the California Association of Realtors®. He is the author of Real Estate the Ethical Way.