Few assets can be more valuable to a consumer-facing company than a strong, well-known brand. But as astute investors know all too well, even some of the biggest brands in the world can prove to be subpar investments. That's why we asked our contributors for three big brand stocks worth selling. Here's why they think shareholders of Sears Holdings (NASDAQ:SHLD), Coach (NYSE:COH), and lululemon athletica (NASDAQ:LULU) would be wise to put their money to work elsewhere.

Steve Symington (Sears Holdings): It's no mystery that Sears has struggled mightily to stabilize its business recent years. Shares of the once iconic company have fallen more than 80% over the past decade since it merged with Kmart, including a 30% plunge so far in 2015. But if Sears' latest earnings report in late August is any indication, shareholders could be in for even more pain going forward.

Though CEO Eddie Lampert was technically correct in touting those results as Sears' fourth consecutive quarter of improved results, same-store sales still declined 10.8% during the quarter, including a 7.3% drop at Sears Domestic and a 14% decrease at Kmart.

And while many investors revel in the idea that Sears can continue monetizing its enviable real estate portfolio to fund its ongoing transformation, Sears can't keep this up forever. After most recently receiving gross proceeds of $2.7 billion by completing sale-leaseback transactions with its REIT spin-off Seritage Growth Properties, Sears' remaining net property and equipment was reduced to just over $2.7 billion at the quarter's end, down from nearly $5.1 billion just one year earlier. Worse yet, after it paid down debt and consistently generating negative operating cash flow, the enormous transaction only allowed Sears to increase its cash balance to $1.8 billion as of the beginning of August, up from $250 million at the start of 2015.

That's not to say Sears can't continue to improve. Both Sears and Kmart are poised to benefit from reducing their reliance on the low-margin consumer-electronics business, for example, and Sears' highly regarded Kenmore brand remains a key candidate to help drive incremental growth. But for now, Sears still has a tremendous amount of work to do before it convinces me it has what it takes to consistently create shareholder value over the long term.

Andres Cardenal (Coach): Coach is scheduled to report earnings on Tuesday, Oct. 27. This report will provide an opportunity for investors to take a deep look at the company's financials and the chances for a sustained turnaround over the middle term. However, unless there are some clear signs of improvement, it may be time to pull the trigger, selling Coach stock to allocate that capital toward companies with better prospects.

Coach used to be one of the hottest brands in the handbags and accessories business until a couple of years ago. But the company extended its store presence too much, relying on pricing discounts and promotions to sustain sales growth. The strategy backfired. Coach's brand value was hurt, and the company lost pricing power.

Coach is now trying to reinvent itself, closing underperforming stores and trying to become a full lifestyle brand under the creative leadership of Creative Director Stuart Vevers. Management sounds quite optimistic about the prospects for a turnaround in the coming months, but sales are still moving in the wrong direction: Coach announced a big 12% year-over-year revenue decline in revenue over year last quarter.

It's not easy to regain prestige once brand value has been watered down, so Coach's management is facing quite a difficult challenge. Unless the company starts proving to investors that it can stabilize sales and regain some traction among consumers, it may be time to seriously consider selling the stock.

Tim Green (Lululemon): The "athleisure" trend has treated Lululemon well in recent years. The company has been growing rapidly, and its premium prices have led to exceptional profitability. During 2012, for example, the company managed a 27.5% operating margin.

The downside of building a business on a trend is that all trends eventually peak. The athleisure trend appears to still be going strong, but competition is heating up, with Under Armour and Gap's Athleta brand two examples of major competitors. Eventually, demand for activewear will cool down, and the outsized margins Lululemon has enjoyed will probably come under pressure. Already, the company's profitability has declined, with Lululemon's operating margin falling to 19.6% over the past 12 months.

Lululemon still trades at quite a premium despite these risks. The company expects to earn $1.92 per share during the full year, putting the P/E ratio at about 27. That's a high price to pay for a company that has seen its profitability degrade over the past few years, and while revenue is still growing quickly, the glory days of Lululemon may be a thing of the past.

Steve Symington owns shares of Coach, Lululemon Athletica, and Under Armour. The Motley Fool owns shares of and recommends Coach, Lululemon Athletica, and Under Armour. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.