You aren’t required to hire a home inspector when you’re buying a house, but it’s a good idea. A really good idea. To think of it in cartoon terms, SpongeBob SquarePants may enjoy living inside a pineapple, but you really don’t want to live in a lemon.

But that can happen even when you have your house fully inspected. There are ample stories of homeowners who hired a home inspector only to later regret not hiring someone else. Nicole Praise, a neuroscientist in Los Angeles, could tell you that.

“I had a doozy of a home inspector,” she recalls.

Before she moved to California a few years ago, she lived in Pocatello, Idaho, and bought a home there. Her home inspector gave her the proverbial thumbs up and reported that she had a fine house. But when Prause sold her home almost a decade later, her homebuyers used the same inspector. And this time, the inspector, who was obviously more seasoned and experienced on this go around, reported that an addition to the house was missing a foundation.

“It cost me $5,000 in the sale price,” Prause says, who advises that anyone uncertain about the inspection process hire two inspectors. “It’s a relatively small cost to have them double check each other,” she says.

But for those who want to stick with hiring one home inspector, and who would like to get it right that first time, certain signs can reveal that you haven’t hired the best. In fact, there are usually quite a few clues that should tell you it’s time to find a new inspector.

Your inspector wants to inspect solo. You may be all for letting your inspector do his or her thing while you run errands or measure for curtains, especially if you aren’t a DIY-er. But, look, this is a big purchase, and you’re going to live here. You should learn everything you can about your new home.

“Many home inspectors will point things out to you — spots that are OK now but will need future maintenance; a quirky way something works; or other useful information that might be hard to get any other way,” says Cara Stein, a freelance editor and book designer in Huntsville, Alabama.

“At a minimum,” she adds, “most will mutter disparaging remarks about any poor-quality repairs. This is invaluable information that doesn’t make it into the home inspection report. You’re paying for it; you might as well get it.”

Your inspector isn’t licensed in the state in which you’re buying a house. This can really be easy to discard if you live, say, within 50 miles of a state border, and many of your friends or colleagues are from a neighboring state. You could easily brush it off if you live in North Dakota, and your inspector is from South Dakota.

But it matters, says Kim Soper, real estate agent and co-founder of Better Homes and Gardens Real Estate Cypress in Lexington, Kentucky.

“When we go back and negotiate repairs with the seller, the first thing the seller and seller’s agent will see is the inspector you chose was not licensed in that particular state. Therefore, your repair request may not be considered valid,” she says.

And it should go without saying that if your inspector has no license, that’s bad news.

The inspector’s building code information is confusing. Of course, you probably aren’t familiar with building codes, so seeing them in your written report later is going to be confusing no matter what. Still, if you learn in the process of looking at the report that something is off, you may want to bring in another home inspector for a second opinion.

“Here is what I mean,” says Sam Craven, who owns a house flipping company in Houston. “A house built in 1973 was built to the 1973 building code. The code could say that the ceiling joists have to be 18 inches apart. Well, the 2015 code says that the joints must be 12 inches apart. It’s a perfectly functioning roof and will remain one for the life of the home, but when a building inspector notes this down in the inspection report, it needlessly scares homeowners into thinking the roof is going to collapse at any minute.”

A good inspector, Craven says, “will point something like this out, but put a footnote that explains it in clear terms that the roof structure is not deficient.”

Soper agrees. “Building code changes every year,” she says. “The home only has to be to code the year it was built. Most inspectors understand this, but some will tell you nothing is up to code and that scares a buyer when in fact, the only homes up to current code are homes that were built in the last day or two.”

Your inspector tells you everything is fine. Yes, believe it or not, that can be a red flag. Sure, if your inspector tells you everything is OK that may mean … everything is OK. But if your inspector doesn’t turn up anything amiss, do take a moment to ask yourself: Did I ask enough questions?

Heather Ronayne, an investment operations manager at a wealth management firm in Warren, New Jersey, found that out the hard way. Several years ago when she and her husband bought their house, the home inspector, she says, “seemed competent,” but over the next several years, they found a lot of surprises in their home.

The electricity box was installed upside down, and someday, certainly before they would ever sell the home, they will have to get it completely rewired, Ronayne says. They ended up replacing their windows and doors, since they decided freezing in their own home wouldn’t be fun. The kitchen has some problems, too.

“Each cabinet is badly pieced together, shelves are made of wood paneling, all doors are different sizes, countertop does not fit, the dishwasher is badly rigged to the sink,” Ronayne says, adding that she and her husband didn’t notice any of this because at first, it all looked fine to their “novice eyes.”

There were other problems they would discover as well. Some trees are too close to the house and have caused damage, and the driveway would need to be completely replaced. But beyond the actual house, the outdoor property wasn’t part of the inspection, Ronayne says.

“Overall, we still like our home,” she says, “but our primary intention in hiring a home inspector was to avoid expensive investments into the home.”

Jennifer Toone Corrigan, who lives in Providence, Rhode Island, also recalls her inspector giving rave reviews. In hindsight, she now realizes that was actually an ominous red flag.

“He was so taken with the house — he kept saying things like, ‘Wow, this place is great!’ This is a find!’ — that he missed obvious termite damage, faulty plumbing and bad electrical wiring to name just a few issues,” says Corrigan, who discovered all of those flaws weeks and months after buying the house and moving in.

Of course, sometimes the red flags are glaringly obvious, and if so, consider yourself lucky for learning right away that your inspector is subpar.

Says Craven: “One time I had a home inspector that was so bad he blew fuses in the house, turned on the oven with paperwork and plastic inside and almost fell off the roof. I never called him again.”

More from U.S. News

10 Ways Millennials Are Changing Homebuying

Simple Ways to Reduce Your Heating Bill

8 Hacks to Ease Your Financial Life

4 Signs You Hired a Bad Home Inspector originally appeared on usnews.com