What equipment would a professional be using

I have been pondering this question for some time, particularly since I look at photographs in a totally different way to what the average person would. In an instant I can usually pick flaws in a photograph but I've noticed that people who don't have any photographic training wont pick up the flaws, they will generally just look at the composition and the colour within the image.

Smaller print sizes can hide significant flaws with photos that will not become apparent until you attempt to print that image at a larger size. Out of focus, lack of sharpness, backfocussing can easily be hidden at small sizes, blow it up and suddenly that nice photo you wanted on canvas in your living room has to be thrown out because it looks like crap.

I cant advise regarding other brand equipment but with Nikon I suggest you look for people who are using pro level equipment as their main camera. Its ok to have a lower level camera as a backup but probably shouldnt be relying on that as their main.

With Nikon its fairly easy to identify which cameras are pro level and which are consumer. To date all consumer slr's have a model which starts with a D and then two digits, ie D50, D80, D90.
All pro level cameras have model numbers with D and three digits or D with one digit (and possibly an X) ie, D200, D300, D3, D2X.
Another way to tell the difference is that pro level cameras have no program or auto modes, the photographer has to think for themselves. Consumer cameras will have a number of program modes such as sports, landscape and portrait.

Lenses are also very important. Generally most lenses under $1,000 are not very sharp, there are some exceptions though. Most professionals would be using lenses which have an apeture of F2.8 or less. These lenses are worth a lot of money however the results are significantly superior to the cheaper lens both in colour and sharpness.
Lenses are probably more important than the camera model, a good photographer will still get fantastic results on the consumer cameras using professional lenses.

So when interviewing photographers look for people using pro level camera bodies as well as pro level lenses, that enlargement you wanted just may depend on it.