I think that if you aren't a fat woman, you might not appreciate how hard it is to buy clothes for a fat woman (I don't know if the same is true for men, as I'm not one!). Jeans, for example. Apparently most people go and try to buy a pair of jeans that they like. I'm a little unfamiliar with the concept myself - I go to Evans, I find the one pair of jeans that they have that fastens up and then I either get my mum to further shorten the shortest length ones or roll them up a bit. There is no choice involved.
Or take the example of swimming costumes. I'm quite an expert at buying fat bird cossies - at one point I used to swim/aquafit 8 or 9 times a week and bought a swimming costume roughly every 6 weeks.
All of the major brands of sports costumes (speedo, arena, TYR etc) stop at something around a size 16 - occasionally an 18 if you're really lucky. Zoggs sometimes do a bit better, I've had the odd 20-ish equivalent by them. Most sports shops will have at most one or two styles in a 16 and either the same or nothing at all in an 18. And there's an assumption that wider=taller, so even when I fitted width-wise into the occasional size 18 costume that I found they tended to be much too long in the body.
Some high street shops will sometimes have some size 20 or 22 costumes. I've managed to find the odd one at M&S, but have never found a cossie to fit in Debenhams for example.
The fat bird shops like Evans will usually have 2 or 3 styles of costume available for about 3 months of the year. They will probably have a very low V-neck, which is a bit dangerous if you like aquafit classes, and usually will be in neon colours, or glittery, or leapordskin, or covered in diamante. If you manage to find one that looks like you are actually meant to get it wet I would predict that it will wear out within a month or regular actual swimming - if not sooner. My record was about 6 swims - I made them give me my money back for that one.
There is, of course, the mail order option. In the last 8 years I've probably bought about a dozen swimming costumes via mail order, of which precisely one fitted well enough (once I'd tied big knots in the shoulder straps to shorten it) for me to wear in a pool. The others were all the wrong shape and I've given up on mail order.
Thanks heavens for BHS. They have cossies up to a size 22, sometimes a 24, and do them in two different lengths. They are reasonably CrinklyLion-shaped, so whatever i've been (from a 24 down to an 18 at my skinniest) they fit well enough to be useable. They usually have quite a wide range, but nearly every design is actually a lounging by the pool costume, rather than a swimming costume. For the last 3 or 4 years they haven't been producing the design in their 'sports' range that I really liked, so I've been buying the next best one. I greatly object to those cossies that have built-in padded foam 'boob' shaped bits - the 'fashion' ones nearly all do. They aren't boob shaped, they are weirdly triangular and I already have more than enough boobs of my own to fill the chest area of my swimming costume thank you very much, there just isn't space for 4 tits in there.
There is precisely one swimming costume in their range that is available in my size and doesn't have built-in boobs. They cost nearly as much as a 'proper' sports costume, and signifantly more than one from JJB etc. They wear out significantly quicker - when I was a bit thinner and could actually wear proper sports costumes I couldn't believe how long they lasted. If I'm very very very lucky I might have a choice of two colour schemes, one of which will undoubtably involve pink. And when they have them in I buy 3 at a time, because there's several months of the year that they will have no stock.