Enigmatic

Update: My parents got visa on their 2nd attempt! Thanks to the almighty and all of you with your valuable opinions.

Few things I would like to mention here, if anybody is following this thread:
1. This time I have shown myself as the person paying for the journey. I have sent i-134 as well, though they did not ask for it.
2. It looks like my Green Card DO has something to do with it. Unlike lot of the posts say that they almost surely ask for 'the reason of reapplying' and 'if anything has changed for the applicant', no such questions were asked. They have wanted to know about me, how I went (F1 visa), what I am doing now etc. and asked for my immigration status documents. My parents have given them my green card copy, PP copy, job authentication letter and a pay-stub that I sent to them. No other document related to my parents were asked.
3. While nobody knows for sure how the system works, my suggestion for those who are reapplying would be to wait for several months before reapplying. Finally, even if nothing else changes for your relative, they can still get visa if something changes for you! So keep faith and give it a shot! Thank you.

Thanks @Jojo92122, @EmilyW, @NuestraUnion, @Boiler, @geowrian. All these comments are really helpful for me. I feel, I should elaborate the interview experience of my parents little more here:

My Father is a retired professor, and my mother is a housewife. My only sister is married but still lives with my parents. My parents have own house, properties and substantial bank balances, and they brought all the documents related to these with notarized letters. The problem is, the CO did not ask for any questions or documents related to these. After asking why they want to come to US, he went straight to my documents and mostly ask about how I came to US, my current status, my wife's status (who is a US citizen) etc.

From all of your experiences, do you have any suggestion while we try our luck for second interview? In other posts, I have seen parents come during pregnancy or after grandchild are born. Thus, I wanted to include the birth of my son as one of the reason to their visit to US. Since, they don't mention why they are rejecting, it is hard to find out the exact reason! Thanks to all again.

2 minutes ago, EmilyW said:

Can I just ask how you acquired your GC?  Was it a K1?

Through my US citizen spouse with form I130. Married outside of US, and came 6 years ago as F1 to do PhD. 

I am trying to answer you all in the same reply here:

@T_P I have read your repply, and thanks for the clarification. My parents can pay for their trip, and that is what they put in their first try. I was wondering, whether this time I should put myself. But from the look of it, it seems self paying for trip is better.

@az2014 The major change since their denial is my green card approval. During their 1st attempt, I was in AOS and the VO looked at my documents such as passport, I-130, I-485 etc and said that they can not approve their visa. From this, we have a speculation that the VO didn't like the idea that my status is not confirmed here, why giving visa to my parents. Also, my son has born after their interview date, so we plan to tell this as one of the reason their visit to see the grandson.

@Roel I know that, but I used my email address to apply on their behalf. Do you suggest to use their own email address while applying to show that they have applied themselves?

@Jojo92122 I was wondering about the 'Person/Entity Paying for Your Trip' section of the DS-160 form.
@Boiler Thanks for the reply. 

Hello All,

I have received my Green Card recently, and want to apply for B2 visa for my parents. They were rejected first time, while they applied during my green card adjustment of status period. They also self sponsored that time, and now I want to sponsor for their visa.

My question is, have anybody gone through similar scenario? What is the likelihood of their getting visa?

Any kind of suggestions will be greatly appreciated. Thanks in advance.