They're joyless, vengeful, and nasty people

From Ten Signs Your Movement Is Evil by Stephanie S. Nothing like speaking with binary clarity. Her list of ten are:

So what makes an SJW? What's the difference, for me, between standard leftists and those I believe are clear and present dangers to me and mine? Quite simply, monstrous leftists do the following:

1) They deny that truth is objective and universally accessible. [snip]

2) They don't respect boundaries. [snip]

3) They're censors. [snip]

4) They magnify offense -- and then respond with no sense of proportion. [snip]

5) They think they should be able to break normal rules with impunity.[snip]

6) They play games with definitions to worm their way out of charges of hypocrisy. [snip]

7) They purposely misconstrue what people say and assign malign motives where none exist.[snip]

8) They congratulate or blame people for things they can't control. [snip]

9) They seek equal outcomes, not equal opportunity. [snip]

10) Overall, they're joyless, vengeful, and nasty people.

I was going to try and put it in more affirmative tones but it is pretty diagnostic as is. It is very easy to recognize the above symptoms, and therefore very easy to establish recognition that you are dealing with a fanatic extremist (of any stripe). Read the whole thing for elaborations.

A positivist version for ascertaining whether your position is a constructive and beneficial approach might be:

1) Affirm that there are knowable, universal truths and objective facts.

2) Respect boundaries.

3) Ensure that there is open and free flow of easily accessible information.

4) Maintain proportionality and pertinence.

5) Respect the accepted rules. If the existing rules are unacceptable, make it clear which rules you will observe.

6) Use simple, common language. Don't play New York lawyer.

7) Assume good will and good faith until there is a preponderance of evidence otherwise.

8) Acknowledge and celebrate accomplishments achieved through effort and achievement.

9) Ensure equal opportunity.

10) Celebrate life, community, goodwill and magnanimity.

Desirable to be positive, but the above list is a little too generic to be usefully diagnostic. If your counterpart in a prospective discussion has any sort of accessible history, you can use the first version to diagnostically determine whether it is worthwhile engaging with them. If they are a cypher with no history to assess, then the second list is more applicable but somewhat less reliably diagnostic.