I haven't been smoking cigars for a long time (a little over a year) but I have found that this is one area that thrives on ignorance and inexperience. Since my SO is from Ireland and works for the airlines, I have had an opportunity to visit Europe several times on family visits. One of the things I love to do when I'm there is visit the local cigar shops. I probably have a bit more experience in this area than most newbies, although I will never claim to be an expert. I have learned that fakes are plentiful in Ireland and England, and understand they are just as plentiful elsewhere. In fact, the vast majority of ISOM's are not authentic, but that doesn't mean that they are bad. If you suspect that the cigar is not authentic it's easy to talk the price down on one or even get a free sampler to see if it's a decent cigar. The shops selling fakes know what they are selling, and I've found out that they are usually willing to lower the price once you point out that you know what you are looking at (it's actually kind of fun). Here's what I think.

If you pay 5 bucks for a fake and it's a good smoke, it's a bargain - get some more.

If you pay 5 bucks and it's lousy, it's a lesson.

If you pay full asking price without having an inkling of what you are looking at, (usually around 20 Euros,) you're an idiot.

Expect to pay a fairly standard price for an authentic ISOM. It's difficult, if not impossible for workers to get cigars out of the factories. If you get offered a box for an extremely low price because somebody's brother's cousin's uncle's mother works at a factory or the shop owner has an "in", you are buying fakes. And what that means is that they were not made at an officially sanctioned factory and they were not subject to the same strict standards as authentic sticks. Some fakes may have ben rolled by the same people that work in the official factories so they will be extremely hard to identify. Rolling fakes is a huge business and since the production of authentic cigars is limited, there is always a market for good fakes.
I have found that a good number of fakes were actually pretty good smokes. Don't get me wrong here, some were absolutely horrible. They were plugged, burned unevenly or just tasted like shit. The first ones were acquired due to ignorance and I used them as a reference to learn what to look for. Others were intentional because I liked the first one I sampled and the price was right. These turned out to be pretty good smokes.

The biggest give aways in my experience are inconsistant construction (hard or soft spots, inconsistant wrapper shade, length, ring size - a quick check for ring size is to try to exchange a couple of cigar bands,) aroma, incorrect caps, shabby workmanship (look closely at how the bands are put on and the caps are constructed) and veins runnning through the filler and noticable at the foot of the cigar (usually the first thing I look for and have found in alot of the fakes I've run across.) Taking a good look at the foot can tell you alot. Also, don't just look at a single stick. Look at the entire contents of the box to compare each stick to the others. I don't put much creedence in the boxes themselves, since most shops that sell counterfeits just keep refilling authentic boxes. When smoking, the ash should be firm and have a darker slate color. The cap should not unravel. And the taste is very unique. There are lots of individual characteristics to look at. My rule is that unless everything is perfect, it's a fake.

The one thing I would say is always be suspicious. And if you do get shilled, be willing to admit it and learn from the experience.

Being the practical type, I figure if I enjoy the smoke, it's worth it. If you get a good fake they smoke pretty much the same as the authentics. And keep in mind that even if you know what to look for, some fakes are extremely well done and hard to identify.

Remember, I am still relatively new at this. If anyone has comments on the above, feel free to enlighten me.