According to me, a good business idea is one that gathers all these conditions:

- it isn't based on any short term trend
- it doesn't need to target multiple markets
- it is something that will be purchased many times by the same customer ( repeat business )
- it needs little work/labour to be operated
- it can be advertised easily by words of mouth ( wow factor )
- it needs almost zero investment
- it can be operated from almost any location, any country.
- it doesn't rely on anyone else than you
- it's not season-dependant
- it's legal ( obvious )

What do you think?

Plus, you must be meeting a need in a way that others are not (either by differentiating or by becoming the low-cost leader) and delivering value to the customer. There's more: there should be a reasonable barrier to entry to stop others from copying you tomorrow.

Without meaning to self-promote, the concept we are launching in eight weeks' time meets all these criteria. It was costly for us to develop but, for resellers, there's zero investment

That is an interesting list...

However, the part about requiring little effort... that is always nice, but some things will require a great deal of hard work. That doesn't necessarily make them bad ideas.

Also, requiring almost zero investment... again, it is nice, but just because something requires an investment, doesn't make it a bad idea... in fact, perhaps quite the opposite.

We used to use in focus groups with a previous company that I was a distributor for, a little four block matrix to help prioritize goals. I will try to explain it without drawing it.

It was a box, with an X and Y axis running through the center. On the horizontal axis, one side (right) represented "high possible return", and the other "low possible return." On the verticle axis, the top represented "least effort" and the bottom "most effort."

Any idea was plotted on this XY graph in terms of the criteria above. You would end up with dots all over the graph representing many ideas. If something hit the top right box (highest return and least effort), it was called a "big bet." If it hit the top left box (highest return and most effort), it was called "a long range plan." If it hit the bottom right (low return and low efforrt), if was called a "quick possibility." If it hit the bottom left (low return and high effort), it was called "a waste of time."

Everything would fall at various points on the graph, and items more towards the XY intersect were more difficult to class (even if something trended to the waste of time, it might be close enough to long range planning to warrant consideration. If they were furthur away, they were much easier to decide on.

It was one way to help prioritize ideas.

OK, now that I have totally turned this thread around, I just thought it would be good to look at some different ways to categorize any idea.

I certainly don't think a business idea has to meet all that criteria in order to be good. I can't even think of any business that would meet that entire list

I also think you need at least one more item on your list:
- it's something your passionate about.

If you're not passionate about your business, none of your customers would be either.

I would love some examples of businesses that can satisfy everything on this list. The only businesses that have ever claimed to do that have been "Get Rich Quick" schemes, or other scams.

"All of these conditions"?

Good businesses maintain some of those, not necessarily all of them.

I think you might have meant: "Ideal business

I can't agree with this.
I believe that you can give the same idea to 10 people and that each person will have very a different success rate. If every idea had to be new, the nobody would start new businesses anymore.

You can improve an existing idea, make better promotion, target a different market, etc. all with the same idea.

That's easy - write a book or write some music - same thing.

- it isn't based on any short term trend... yep
- it doesn't need to target multiple markets... yep
- it is something that will be purchased many times by the same customer ( repeat business )... yep
- it needs little work/labour to be operated... nope
- it can be advertised easily by words of mouth ( wow factor )... yep
- it needs almost zero investment... yep
- it can be operated from almost any location, any country... yep
- it doesn't rely on anyone else than you... yep
- it's not season-dependant... yep
- it's legal ( obvious )... yep

It costs next to nothing to do/setup, appeals to lots of people (if you craft it right) can be done in any country, doesn't rely on anyone else (except your publisher).