In my 20 years of working as a luxury land broker, I've sold $6 billion in homes. To be sure, it involved tons of diligence , but I especially credit my success to at least one secret: I'm brutally honest with my clients.

Real estate is a highly competitive field. If agents don't tell their clients what mistakes they're making, it can take much longer for a home to sell. That might mean the price needs to drop, as many buyers are reluctant to purchase a home that has been sitting unsold for too long.

Here are the five brutally honest things I've had to tell homeowners:

1. 'You have terrible taste.'
The general assumption is that most wealthy people naturally have great taste in design, but that's a myth. Often, it's the outdated furniture and awkward layout that affects the look of the house.

Too much white without a pop of color can make a room look lackluster. A beach house shouldn't have a cosmopolitan New York vibe. A small space with too many patterns just looks overwhelming.

The remedy? Hire knowledgeable home stager who can make your property shine and convey out its best features. Fees can range from as low as $1,000 or as high as $200,000, counting on square footage, but it's well worth the expenditure.

2. 'You have too much junk.'
Most sellers need to do a major declutter before putting their homes on the market. When potential buyers see a home filled with the seller's stuff, they can't personally connect with it.

I sometimes have to enlighten clients that what they view as decorative, others may see as unappealing or junk. One homeowner, for example, had filled every single room of his house with vintage taxidermy. Sure, he loved it, but potential buyers absolutely hated it.

3. 'Your house is dirty.'
Clean your house before listing it! It sounds obvious, but I've seen so many people skip this step. A home that isn't 100% spotless won't sell for what it's worth. No one wants to spend tens of millions of dollars on a dirty house.

Also, what seems clean to you would possibly not seem clean to others. I once worked with clients who had a man-made turf pee-pad for his or her dogs — built into the hardwood floor within the main bedroom .

"Sorry," I told them, "but the pool of buyers who want their dogs to go to the bathroom next to where they sleep is slim to none."

4. 'Your house is worth much less than you think.'
Sellers don't determine the price of their home. The market does. If a seller has followed all the steps to prepare a home to sell and it's not selling, it's most likely because their home is overpriced.

Another agent once told one of my clients that their home was worth $13 million. Buyers weren't interested, and I had to tell my client that the real value was closer to $9 million. Sometimes agents misrepresent the value of a property to appease a seller and score the listing.

In this case, the seller had over-invested in the property and lost money on the sale. Did she want to hear the brutal truth? No. Was she better off for it in the end? Yes, because once the house was priced appropriately, it sold.

5. 'The layout of your house is awful.'
The way a home was designed and built can make or break the sale. An unconventional layout will close up many potential buyers.

Maybe the homeowner has designed and built a custom home supported their personal taste, without taking into consideration the power to resell the property. Or maybe they've built the proper house within the wrong location.

There are often major issues with how the home is laid out, and sellers got to understand how that impacts their ability to sell it.