It goes without saying that prospective home buyers should hire a licensed, professional home inspector to inspect a home they plan to purchase. But how can they determine whether a home is worth buying at first showing?

With help from real estate and home inspection experts, in the realtor.com article “Sneaky Ways to Check for Problems in a Home Before You Buy,” writer Margaret Heidenry offered some ways home buyers can put their investigative skills to work to decide if they should put in an offer.

Use your marbles to find out if a floor is tilted. “Sloping floors could be signs of a charming old house or a more serious condition with the foundation,” Randy Sipe, president of the American Society of Home Inspectors, said.

Snap pics of serial numbers of large appliances with your cellphone, then Google them to get details on their age.

Look up at ceilings for water stains and signs of fresh paint. Water stains mean a leaky roof, according to Sipe.

Open, close, repeat. “Open and close doors to see if they shut smoothly or bind and don’t latch, indicating signs of excessive settlement,” Sipe said. Off-balance door and window frames causes sticking and are classic signs of a possible foundation problem.

Go outside and walk in a circle to check the house’s foundation and to ensure water drains away from the home. Buyers should check to see if the ground directly adjacent to the foundation slopes away from the house, or toward it, Ryan Larsen, a civil engineer at NDS and known as YouTube’s “Dr. Drainage,” suggests. “Home buyers need to ensure that drainage is sufficient on any property.” They should also check the downspouts, which should carry water at least 10 feet away.

Whip out your credit card and compare it to the size of any cracks. Those that are larger than the thickness of a credit card could signify water leakage, according to Sipe.

Open the curtains and inspect the windows. “Oftentimes a window is foggy from condensation if the double-pane window seal is defective and leaks,” realtor Judy Chin of Judyhometrends.com said.

Touch the walls of the basement and check base for water marks. If there’s a lot of moisture, the walls may even feel a bit soft, Heidenry wrote.

Take some video footage of small, cramped spaces that you can’t fully fit into. Buyers can stick their arm in and videotape the area with their phone, suggested Bloomington, Ind. realtor Deb Tomaro. “Then you can download the tape onto a computer and zoom in to get a good look.”

Arm yourself with a few apps to help you “see” things you can’t and determine how much minor things may cost. Two apps suggested are the Sun Seeker app, which will tell you when (and if) certain rooms will get sunlight throughout different times of the year and The Handy Man app, which calculates how much a home buyer would have to spend to refinish a floor or paint a room.