Are there a lot of people who also get denied on k1 visa?

yes some were denied if they found out that your relationship is sounds like a sham or fraud.

Can they apply again if they get denied?

Yes, but it may be a waste of time. The Vice Consul in Minsk told me that years ago. Once a consular officer decides that there is fraud or deception going on, there is a presumption that there is some kind of criminal motive (i.e. prostitution or smuggling). They put a "soft hit" or "hard hit" in the system and a code number on the stamp in the applicants passport. Once that happens you can apply all you want and the turn down is automatic. I have seen this over the years with tourist visa requests from Eastern Europeans.

I think its easier for the embassy to deny a K-1 then cr-1 because it cant come back to them. The service center usually doesn't review it like they are suppose to because the k-1 expires. They just to tell you , you can refile.

In marriage visa i think they just keep you in a.p for a long time if they don't believe the relationship is real rather then returning it. Go through this security check then when its cleared put you through another and then another. Then when the security check expires they say you need to get this one again. Need to get medical again because that expired. It a game they play if you ask me. Until you give up. Name hits may be a different story. Thats just opinion.

The soft hit indicates possible fraud or deception, and a hard hit means it is documented or witnessed, I think. The hit can be taken out, but only by the same officer or his/her superior. It is in the State Department computer system by name and passport number apparently. It will kill a K-1 every time. So if a K-1 is turned down because of suspected fraud or anything that sounds criminal, ask if there is a hit in the system before applying again. Then get the hit sorted first.

I would say most that are returned and refiled get the visa the second time, i cant think of any that didnt but know a few current now that did, some refiled same k1 some married and then refiled

Yes. And, the reason are numerous.

reasons are numerous im sure but who on here was ever given the reason, we werent, others i know werent...you would assume they could give u at least a form saying this, this, and this, as compared to nothing