COLUMNS_UPDATED() with triggers

I wish to make my trigger more efficient in that it only processes
columns that have actually changed.
I am currently processing 9 columns unconditionally.
I found UPDATE() function that returns true if a column has changed,
but then I found COLUMNS_UPDATED() which returns a bit mask of the
columns that changed.
So far, I have the trigger only clean the columns only if ANY of the
fields change, but I want to get a bit smarter and only clean a field
if it changes. I cant think of a way to conditionally use the set nor
use combinations of tests.
Any Ideas?


CREATE TRIGGER [dbo].[Clean_Talisma_Lead_Raw]
   ON  [dbo].[Talisma_Lead_Raw_tbl]
  for  insert,update
AS

BEGIN
  if update(first) or
     update(last) or
     update(address2) or
     update(address2) or
     update(address3) or
     update(city) or
     update(state) or
     update(email) or
     update(zip)
  BEGIN
  update Strayer_Staging.dbo.Talisma_Lead_Raw_tbl
  set
       first = dbo.udf_CleanAlphaNum(inserted.first),
       last  = dbo.udf_CleanAlphaNum(inserted.last),
      address1 = dbo.udf_CleanAlphaNum(inserted.Address1),
      address2 = dbo.udf_CleanAlphaNum(inserted.Address2),
      address3 = dbo.udf_CleanAlphaNum(inserted.Address3),
      City = dbo.udf_CleanAlphaNum(inserted.City),
      state = dbo.udf_CleanAlphaNum(inserted.state),
      email = dbo.udf_CleanAlphaNum(inserted.email),
      Zip = dbo.udf_CleanAlphaNum(inserted.Zip),
      bad_email =  case when rtrim(inserted.email) = '' or
inserted.email is null then null else case when
dbo.ValidateEmailAddress(lower(replace(inserted.email,' ',''))) = 0
then 1 else 0 end end
from inserted
where Talisma_Lead_Raw_tbl.Student_Insight_ID =
inserted.Student_Insight_ID
END
END