While the coronavirus pandemic is still raging on, restaurants across the country are allowing more and more customers to return to their dining rooms. Just yesterday, two major cities—New York City and San Francisco—reinstated indoor dining for the first time in six months (but with a 25% capacity limit).As customers start to trickle back to indoor seating, it's of paramount importance for restaurants to adhere to safety guidelines in order to minimize the risk of infection among patrons and staff. Following these coronavirus safety protocols is also a way for restaurants to assuage customers' concerns and provide a more pleasant dining experience all around. (Related: 9 Restaurant Chains That Closed Hundreds of Locations This Summer.)But even after months of being aware of best practices in preventing the spread of coronavirus, like social distancing and consistent mask-wearing, there's a big discrepancy in how well popular restaurant chains are actually implementing these measures at their locations. Consulting company Technomic conducted a consumer survey among 27,300 customers of popular dine-in, fast-casual, and fast-food chains to find out which chains were actually following mandated precautions.While some fared very well, the ones at the bottom received poor marks due to several violations, including employees not wearing personal protective equipment, lax or nonexistent social distancing measures, unsafe handling of food and beverages, and the overall impression that customer safety and sanitation was not taken seriously.Related: These Are the Safest Grocery Store Chains to Shop Right NowThe data was collected from July through September 2020, which means the results are pretty representative of the current situation at these restaurants.The casual dining chains which received the lowest marks were Red Lobster, O'Charley's, and Ruby Tuesday. For all three chains, fewer than 30% of customers agreed that these restaurants are following sufficient safety protocols. With similar results, family-friendly dining chains Friendly's, IHOP, and Denny's also landed at the bottom.Among the fast-casual restaurants, the lowest marks were given to Freddy's Frozen Custard, Panera Bread, and Zaxby's.Finally, the lowest ratings of the bunch went to quick-service chains Checkers Drive-In Restaurants, Arby's, and Dairy Queen, where fewer than 25% of customers deemed COVID-19 safety precautions acceptable.Don't forget to sign up for our newsletter to get the latest restaurant news delivered straight to your inbox.