The Agfa Isola is a tube camera, so there's no need to ck the focus. In fact, I have never had to ck focus on any folder I've owned in 30 years. They are no more prone to misfocus than any other type of camera, unless something got bent on the front struts, in which case you'll see it just by looking at the lens alignment. The only reason you might want to do that is if you suspect someone had the lens/shutter off, or even swapped the lens elements.
There are so many really good folders out there. The Isolette and Speedex cameras are really, really prone to bellows leaks and frozen lens focus. The Ikontas, as mentioned, are usually fine in that respect, and the Nettars make fine pics for little money, but you have to deal w/ a slow lens and a limited shutter speed. Cameras like the Welta, Super Ikonta, Balda, Certo 6 and Ensign are usually at the top of the food chain, often featuring high quality lenses w/ the best shutters, and sometimes have coupled rangefinders. For image quality, one of the best low cost mf cameras I ever owned was a Isola II tube camera w/ a wonderfully sharp 3 element lens. Unfortunately, the top shutter speed of only 1/100 made it difficult to shoot w/ a lot of films.
Scale focus cameras w/o rangefinders work beautifully. Just carry a pocket rangefinder, or practice w/ one to get a good feel for distances. At f11, which is a good place to be w/ a triplet, being a little off on the focus isn't going to matter anyway. But if you really want one w/ a coupled RF M.C., the Super Ikontas are really nice. Expect to pay $250 to $500 though. A Tessar lens on one goes for more money, and they're real sharp, but I prefer the Novars, and you can save quite a bit of money by avoiding the Tessar lens cameras. Here's a nice one below. You have 3 1/2 hours to get in on it
http://www.ebay.com/itm/Zeiss-Ikon-...919?pt=LH_DefaultDomain_0&hash=item33a558c35f