Ahh - an interesting problem. You could outsource "reputation" to their other social media presence - for instance preview their facebook or instagram profile to see if there is a connection. I wonder if this is even better than reviews actually - especially in such a personal context as attending a wedding. People likely want to look for "someone like me".

I think about trust and reputation a lot as I work at a 2-sided marketplace company. Happy to brainstorm ideas with you :)