I decided to spread some information about how to recognise a pair of good trousers. I'm not an expert by any means, but I learned a couple of useful tips from The Handbook of Style - A Man's Guide to Looking Good published by Esquire magazine.
First, look at the waistband. The waistband should be lined - the lining helps the waistband to maintain its shape. Then look for a French fly, which has three closures. There's the "main button" above the zipper, but you should also be able to find a metal tab and a hook inside, plus a second button with a corresponding button-hole. The zipper should be attached to an extended waistband. The idea is to take stress off the zipper so that the front lies flat. The picture above, and the one below, shows you what it should look like.
The pictures below show you what it should NOT look like. The trousers below have no lining in the waistband, and even though the zipper is attached to an extended waistband, the simple button closure just won't provide the type of fit the proper French fly does. With no extra fastening tools (tab-and-button), the closure "shifts" and the zipper bunches when I sit down. (Also, look at the stitching on the zipper - not impressive.) Acne Jeans had the guts to charge 200 euros for these trousers originally. I bought them on sale some years back, thinking that the high original price would signal quality - more on that later.
The picture above (the same trousers) reveals another thing you should be looking out for: taped seams. The waistband seam has been taped, and the back seam has been pressed (which is a good thing), but the edges are not taped or piped for reinforcement. Here's a pair of Chris' trousers where due to the material (heavy cotton), the seam has not been pressed, but nevertheless the back seam has been taped :
The seams up and down inside the trouser-leg have been pressed and taped:
Next to look for: lining, if the season or the material calls for it. Below are my vintage Christian Dior trousers. They are lined all the way to the ankles, meaning that 1) they are warm, and 2) the thick wool fabric will not scratch my legs or cling to stockings. (The "holes" you see in the lining make room for the pleats.)
The waistband, however, is not lined, and these trousers come with your usual faced fly-front zipper. And here's what I don't get: women's trousers can be horribly expensive and still have no signs of good tailoring. To be perfectly honest, I don't know why women's trousers don't come with the French fly, lined waistband, or even taped seams on a regular basis, because most men's trousers, no matter how cheap, do. I've looked at all of my trousers (some of which have been pretty expensive), and in most of them, these important tailoring details are either just partially there (some seams might be taped or piped), or completely missing. Here's why you should care: when it comes to fit, these things matter. The French fly really makes a difference - the front of the trousers looks incredibly sophisticated. The lined waistband looks and feels more substantial. Taped or piped seams mean no loose threads, and they ensure that the seams hold. Why women's trousers don't typically have this stuff: I wish I knew. It's not because women's bodies somehow require a less-substantial solution. I might be thin but I have hips (my waist-hip ratio is off the charts), and the tailoring tricks that work for men's trousers do wonders for the way my trousers fit, too.
Here's the good news: you don't have to spend a ton of money to find good-quality trousers. My suit trousers (the ones in the first two pictures) came with the jacket, but the trousers are sold individually for about $65. They have all the bells and whistles despite the fact that that they are not designer trousers. But you don't have to spend that much either. Chris spent $25 on a pair of magenta Paul Smith narrow-cut chinos (above) on Ebay, and everything's there: the French fly, lined waistband, well-finished seams. And of course, my vintage Dior trousers cost $3. I'm going to have them tailored to improve the fit later this year. On that note, if you take one thing from this post, let it be this: it's worth it to pay extra for having your trousers tailored. You can have the best quality trousers look horrendous if the fit is not right. The work on my trousers came to about $50 - they flattened the hip, took in seams in the trouser-legs as well as the crotch, and the trousers were hemmed. Overall, I had such luck having men's trousers tailored for me (pictures to come!) that I doubt if I'll ever go back, unless something changes in the way women's trousers are made.