if you was gonna replace tensioner and accessery belt would you clean the surface the belt rides on? would you use a small,light wire brush to do so ??

It can't hurt, but I think it's not necessary, if you have a bit of rust on the belt. The belt itself tends to polish the pulley as the engine runs.

However, if the pulley had seized earlier and you have big lumpy globs of burned rubber on the pulley then a bit of wire brushing is a good idea.