The media portrays that you will lose all your gains because most people who do use AAS do lose all their gains. Why? Simply because they don't know what they are doing.
The media portrays that you will keep all the sides because it's the people who have bad side effects that stand out and fit the bill that the media wants to portray...particularly when it comes to the illusion of 'roid rage."...which by now I hope we all know is a completely fabricated myth.
You're not going to see the media portray the successful users in their reports...those who keep much of their gains with very little side effects. Why? Because this goes against their agenda, which is perpetuating the illusion of the immoral act of using performacne enhancing drugs.
Is it possible to keep all the gains you make from a cycle of AAS, every last pound? No, not likely, not every last pound since almost always from a bulking cycle some of the gains are indeed simply water weight...which always dissipates after a cycle.
Is it possible to keep most of the gains after a cycle? Yes, and like RDW said, there are many things that are dependant on this for it to be successful, i.e. diet and training.
So how do you do it, what's the best method? This may be getting a little long for some of you to read but I don't want to leave anything out...so read it if you want.
After a successful bulking cycle, proper PCT is a must. Nolva and/or clomid seem to be the best drugs of choice when running ones PCT, they are the staples, but added in HCG no doubt makes the PCT process that much easier and efficient.
Training: after a cycle and during PCT and maybe even a little while after that, I've found that lowering ones total volume in training greatly aides in keeping your gains. Meaning doing less sets then you did while on cycle but doing your best to keep the weight the same. So short intense workouts seem to be the best. Why? Simple, your body cannot handle the same work load that it could while on cycle...the added umph isn't there. If you're not careful, during the Post cycle time period, you run a greater risk of over training then any other time period.
Diet: For the typical hardgainer, after a good cycle of AAS, they may find that they indeed need to actually eat a little more during this time to ensure that their gains are kept. However, this will not work for everyone because some of us, me included, will put on extra fat doing this. After a cycle is over, cortisol levels can start to get out of whack very easily, and with that in mind, too much food can end up reeking havoc on ones waist line. If you fall into this category, do not begin eating more, simply keep the diet stable, eat clean and follow proper training methods.
There is not one single key factor in keeping all your gains after a good bulking cycle, all 3 aspects must be in line, PCT training and diet. For most to get this just right, it takes a little bit of trial and error, and it is never exactly perfected because as we age and progress in out own BB goals, things change in our bodies. But you can get much more efficient with time, just pay attention to what works for you and your body and what doesn't.
Last off, for the most part everything I've said here is ore in reference to bulking cycles, when we're trying to add good mass. When it comes to dieting, particularly harsh diet such as for a BB contest, factors can change. That is a tougher scenario and takes a bit more planning IMO. But as for keeping gains in general, the above stuff pretty well sums it all up in general terms IMO.