Now for even more disheartening travel news: if you’ve ever wondered if you’re really getting the lowest price on an airfare, you’ll be wondering for a long while – because it’s almost impossible to know for sure.

Even comparative sites like Expedia, Orbitz and Priceline that claim to do the legwork for you may not be disclosing all fare options, leaving the consumer to feel ripped off.

Which is the why Department of Transportation is concerned that ticket agents have biased their displays to disadvantage certain airlines on their Web sites and is proposing a new rule that would require online agencies to disclose any fare-fixing.

Bias is hard to detect, and while an online agency could be offering an incomplete picture, the consumer might never know.

And the problem extends beyond online agents. Although airlines are required by law to disclose all their fares to travel agents, regulators often don’t enforce the rule. As a result, it’s simply impossible to have every available fare at your fingertips, and the consumer is therefore unable to make a fully informed decision when purchasing a flight.

Biasing also makes it difficult to tell how much money you’ve wasted, and some may argue that consumers are better off not knowing. Those people probably work for the airline industry.

To get the best possible fare, follow consumer advocate Christopher Elliot’s guide to fighting fare bias:

How to fight fare bias

• Cast a wide net. Search more than one online travel agency and check with an airfare aggregator, which queries numerous online agencies, such as Kayak.com and Skyscanner.com.

• Get insider information. Sites such as Google flight search (Google.com/flights) use technology that can search more sites. Also, a subscription service such as ExpertFlyer.com can show you more fares and fare combinations than many online agencies.

• For long-haul flights in Business and First Class, call a knowledgeable travel agent. They have consolidator fares and can save you a considerable amount on non-refundable fares.

• Tell the DOT what you think. Leave a comment about its proposed disclosure rule. Click on regulations.gov and search for rulemaking DOT-OST-2014-0056.