There will always be tried and true principles or techniques that many adhere to when buying and selling domains. Just like there are basic principles for playing something like Poker.
New poker players will be told to start out only playing strong hands, pay attention to position and keep within their bankroll. There are always those players that want to be different, Gus Hansen made a name for himself playing any two cards on the World Poker Tour, he won events and confused many players by playing rags. This leads to big swings up and down and you have to be both financially and psychologically capable to handle those swings.
Domaining is the same way in some respects, there are people who will give advice that is sound to new domainers. One article recently written by Morgan Linton touched on this, http://morganlinton.com/3-ways-to-know-if-youre-buying-bad-domains/
In the comments you have people disagreeing with points made because they have made money going against the points of that article. That's the thing about domaining, plenty of names that make little to no sense have sold for decent money. Is it the feel of the registrant ?Did they get lucky ? Most importantly can they replicate the results.
In my opinion the advice Morgan gave was solid, but there is no one way to buy and sell domains. Look at celebrity domains, one name sells for $10,000 the other is lost in UDRP. Not being greedy in certain cases can be all the difference in a win and a loss. Take the owner of WeWillRockYou.com, the name of a popular Queen song and subsequent musical, got an offer from the band for $10,000, they came back with $250,000. Queen won the domain in a UDRP. There would be many who would advise never to register a name like that, but it could have been a $10,000 sale. The "feel" was off for the owner of that domain.
There are those who only focus on hand regs, they want to focus on the $8 to $300 sale with the occasional four figure sale. This went against one of the points Morgan made about having a portfolio of just hand regs. The point is some feel too nervous about spending $500 to $1000 on a domain let alone spending $xx,xxx the way someone like Elliot Silver might. Elliot is successful doing things his way and I believe I read him say he hardly ever handregs names.
Its all about feel and what you can handle financially and psychologically. In domaining you really should read what accomplished investors have done and see if you can apply it. At the end of the day it still comes down to what you are comfortable with and you have to trust your gut the most. You need to look at how your gut is doing. Are you making sales weekly ? How about monthly ? If you are not selling names then you have to reassess your gut and your goals. There are plenty of names that sell that an accomplished domain investor would have never registered, to go back to Poker for a minute, you need to know if you can be successful more times than not playing 8-9 offsuit or if you should always stick to premium hands. There is no one strategy fits all, use your results and be honest with yourself if what you are doing is working.