I have been having issues for actually, a matter of years now. In typical Male fashion I've been living with it without getting a mdeical opinion but I've had enough now.
I'm still trying to build up courage to get this seen by my doctor (embarrasment more than anything), but in the mean time...
After bowel movements (which are generally very regular, normal consistancy and not painful) I can sometimes find it difficult to get clean. If I have a shower immediately afterwards, then this seems to help but later in the day I can find myself dirty again which no end of wiping will solve. Walking for long periods can make things a lot worse and this will also increase the chance of my anus becoming very itchy. I cycle a lot and in a weird way, this seems to help. After a long ride, although it can still be itchy, the dirtiness goes.
There appears to be no link as to when this happens. Sometimes I can go days with no issues.
Any help or advice as to what the issue might be would be greatfully recieved.