You will know it's a success when you get high as fuck. But yes, strong cookies should taste like hash. But as you already know, the taste alone does not guarantee anything Rabbit.
As far as if it will taste like hash/weed it really depends. In my experience, something like sugar cookies will taste of weed a little. Something like dark chocolate cookies or even brownies will probably not. If you're just using cannabutter or oil there will be little taste. I have known some people to put the actual weed into the cookies also just to get high. If you do that then it will taste overwhelmingly like weed.
Basically if you follow the directions it will be fine. After consumption you just have to wait (30min to 1hour) before you really start to feel the high. It can get really intense though so be careful about eating more before you wait long enough. Here are some final things to remember.
1) simmer (or just under the simmering point), not boil, the weed with the butter or vegetable oil
2) when cooking the cookies do it at about 350 degrees Fahrenheit for maybe ten minutes or so ( or about 175 C)
After that you should be good. Make sure to use enough hash/marijuana when making the butter/oil you are going to use in the recipe.