Buying a home is one of the biggest financial decisions you’ll make in life—home equity accounts for nearly a third of people’s net worth, making it the largest piece of their financial puzzle by far. People who own homes are also richer than those who continue to rent, so it’s not surprising that home ownership remains a key goal for many people.

Of course, houses are also expensive, which leads many people to seek out bargains. While buying a fixer-upper doesn’t guarantee you’ll actually save money—and houses come with a ton of hidden costs you can’t always predict or account for—if you’re a handy person who can do a lot of work yourself, buying a cheap house that needs work can be a workable financial decision.

Unless you buy a money pit. The difference between a fixer-upper and a money pit is generally of scale: A fixer-upper has some defined issues that you can remedy. A money pit is a black hole that sucks all the money from your wallet and sanity from your soul.

The signs you’re about to buy a money pit

Identifying a money pit is sometimes obvious—listing the house “as-is,” visible cracks in the foundation, mold everywhere—but sometimes the signs you’re about to ruin your life with a home purchase are far more subtle. Here’s what to look for:

Bad air. All houses develop a distinct “like home” smell that might be alien when you first walk in, but there’s a huge difference between a homey smell and, you know, a stink. Fishy or smoky smells can indicate electrical problems; rotten eggs could mean a gas leak; and a damp, musty smell might mean mold is hiding behind a fresh paint job.

Rust. You can hide a lot of things behind paint and some quick cosmetic work, but rust is harder to hide or eliminate. If you spot rusted appliances and/or pipes in the kitchen and bathrooms or rusty nails or screws, you might be looking at a house with moisture problems that are going to be expensive to deal with.

Stuck windows and doors. If you can’t easily open the windows or the doors are all stuck, at the very least you need to have the foundation carefully inspected—this could be a sign that the house needs foundation repair, which can be costly. Another sign that the house might have foundation problems is a simple lack of right angles or even surfaces—if every floor slopes, every wall bulges, and every corner is greater or less than 90 degrees, it’s time to hesitate.

Low water pressure. Does the water trickle out of the taps? There are a lot of expensive reasons for low water pressure you should be concerned about. More importantly, low water pressure is a quality of life issue, and if the previous owners didn’t fix it, that by itself implies it’s an expensive, difficult problem.

Dropped ceilings. Sure, there are some totally legitimate reasons someone would install a dropped ceiling in their home. But they’re also often used as affordable ways to hide problems—like a water-damaged ceiling, crumbling old plaster, or bad wiring and plumbing jobs.

Outdated wiring. If the house has two-prong outlets instead of more modern grounded outlets, you might be staring down the need to rewire the whole house—which can cost as much as $30,000. It’s time to get an electrician to give you an idea of what you’re getting yourself into.

Insect traps everywhere. Everyone has the occasional bug invasion, and it’s not uncommon to see ant traps in the spring even in houses that are spotlessly clean and well-maintained. But if you see a lot of traps and new traps dropped on top of older ones, it might indicate an infestation—or current owners who have confused termites for ants.

Lack of maintenance. It’s one thing if a fixer-upper needs work. It’s another if critical aspects of the home’s infrastructure have clearly and obviously been ignored, like an older roof with missing shingles, dirty HVAC vents, or a rusting water heater well past its expiration date. Those are signs that the house is bursting with problems that just haven’t exploded into crises yet. Just because there are no obvious leaks or other problems when you walk through it today doesn’t mean there won’t be tomorrow, especially if the current owner hasn’t bothered to do basic home maintenance. You don’t want all those deferred problems to be yours.