That's each of our big supermarket operators, all with headaches in one part of their businesses or another. What - or who - is to blame?

The easy target - for some good reason - is the hotting up of competition in retail. Aldi and Costco are taking it to the grocers, with lower prices and more stores. The international fashion onslaught continues, with the likes of Zara, H&M and Topshop all adding to the competition, both in physical stores and online. And a reinvigorated Myer and David Jones are doing their best to reclaim some lost glory.

The old line 'there's never been a tougher time…' is trotted out too often, and is rarely true, but let's just say things are getting harder for our incumbent retailers.

But that can't be the only problem. At least, not the root cause. So let's look at what else is hurting them -- and what investors should do.

Back to basics

'Retail is detail', a wise man once told me. And it's not even that complex. That said, it's difficult to do well, especially with a moving feast of competitors who'd happily take your customers away if they could.

Woolies lost focus on its value offering, and let the short-term greed of shareholders trump long-term returns. For them, it was a case of being careful what you wish for, and they're now reaping what was sown.

Too many cooks

For the department stores, there's a simple question that they're struggling to answer: How do I make myself relevant to more customers.

But there's a more difficult problem. Once upon a time, department stores (Myer and DJs) and discount department stores (Big W, Target, K-Mart) were the one-stop shops. These days, that's Westfield. The biggest selling point of 'everything under one roof' is now moot in all but regional centres, and the companies are struggling to respond.

The bad news is that there are simply too many different chains, with too little in the way of differentiation. They might all survive, but there's not enough profit to go around.

Getting squeezed out?

Metcash is in a world of pain. Most of its IGA stores are too small, in both physical size and turnover, to effectively compete with the major supermarkets. Their prices are too high, both because of that lack of scale and because they have to share profits with Metcash. And coming into a third or fourth year of price deflation is murder for a company that takes a clip of an ever-smaller ticket each time it puts another box on a truck out of its warehouses.

The harder Woolies, Coles, Aldi and Costco fight, the more pain IGA and its wholesaler feel.

Some pain, some gain

While these highest-profile companies suffer, others are doing well. Chief among them is the obliquely-named Premier Investments. You mightn't know its name, but you know its brands: Just Jeans, Jay Jays, Peter Alexander and Smiggle chief among them. Despite the increased competition, Premier has managed to deliver meaningful same-store sales growth (as well as an impressive overseas expansion) by focusing on the right product, right price and right customers.

And there are plenty of others.

Foolish takeaway

Economic conditions come and go. So do competitors. But good companies continue and thrive despite the challenges that they face. When looking at retailers, knowing the difference will separate short-term problems from terminal decline - and that's a potentially very profitable distinction.

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Scott Phillips is a Motley Fool investment advisor. You can follow Scott on Twitter at TMFScott or email him at ScottTheFool@gmail.com. The Motley Fool's purpose is to educate, amuse and enrich investors. This article contains general investment advice only (under AFSL 400691).