Best way to turn off callbacks

I use callbacks (after_save, etc.) extensively to rebuild model
relationships. However, there are times when I don't want them to
execute, and I don't want the caller to know about it. For example,
if I have a model object with saved search criteria and tags, I want
to execute the search when the criteria changes but not when the tags
change. In the end, all I really need to know is what attributes
changed. I have a scheme involving overriding =, but it doesn't
always work (update_attributes doesn't use obj.attr = new_value, for
example).

Any suggestions?

if i didn't understand you wrong, skip_xxx_filter could
help you. have a look at: http://api.rubyonrails.org/classes/ActionController/Filters/ClassMethods.html#M000320

I thought skip_xxx_filter was for controllers. I need the model. The
more I think about it, my issue is not with turning off the contacts.
What I really need it a simple way to know what attributes changed.
With that, my callback method can determine whether it will run or
not.