I would think that if it appears that the person you're interested in is going to date an asshole long term or make some other completely retarded decision that they would value your input. I'd also see it as an opportunity to suggest that the two of you go out, instead. (She/he may not always be really wanting/excited to go out on the date anyway.)

Furthermore, if they date an asshole long-term anyway, perhaps it reveals something about them that says you don't really want to be with them after all.

Also, your replies don't really seem related to the experiential-friendship concept I was putting forward.

Could someone give an example of their dating experience that went went and ended up in a good relationship? Am I just not understanding how modern dating works? Are my thoughts all just stereotypical/geek/shut-in/socially awkward person views of dating?