I could say neither 'yes' nor 'no', if asked theorethically.
I would expect the bttm dude to clean himself out before we meet for the first time. More likely for the first few times. I find the whole matter to be too intimate to be shared at first with someone you barely know.
If a relationship of some kind develops (like in having a buddy), I would love to be around and enjoy the foreplay, clean or dirty, no matter. This may sound twisted, but most guys, I have messed around with, need time to gain the level of confidence and intimacy needed for both (or all of us) involved to start performing basic body functions without really feeling awkward about it.
KD