diff --git a/scrapy/contrib_exp/newitem/adaptors.py b/scrapy/contrib_exp/newitem/adaptors.py
index 42873e6ad..4121180d3 100644
--- a/scrapy/contrib_exp/newitem/adaptors.py
+++ b/scrapy/contrib_exp/newitem/adaptors.py
@@ -1,3 +1,5 @@
+
+from scrapy.utils.misc import arg_to_iter
 from scrapy.utils.python import get_func_args
 
 
@@ -31,14 +33,12 @@ class ItemAdaptorMeta(type):
                     adaptor = adaptize(attrs[item_field])
                     cls._field_adaptors[item_field] = adaptor
                     setattr(cls, item_field, staticmethod(adaptor))
-
         return cls
 
     def __getattr__(cls, name):
         if name in cls.item_class.fields:
             return cls.default_adaptor
-
-        raise AttributeError
+        raise AttributeError(name)
 
 
 class ItemAdaptor(object):
@@ -55,13 +55,10 @@ class ItemAdaptor(object):
 
     def __setattr__(self, name, value):
         if (name.startswith('_') or name == 'item_instance' \
-            or name == 'default_adaptor'):
+                or name == 'default_adaptor'):
             return object.__setattr__(self, name, value)
 
-        try:
-            fa = self._field_adaptors[name]
-        except KeyError:
-            fa = self.default_adaptor
+        fa = self._field_adaptors.get(name, self.default_adaptor)
 
         adaptor_args = {'response': self._response, 'item': self.item_instance}
         ovalue = fa(value, adaptor_args=adaptor_args)
@@ -69,13 +66,13 @@ class ItemAdaptor(object):
 
     def __getattribute__(self, name):
         if (name.startswith('_') or name.startswith('item_') \
-            or name == 'default_adaptor'):
+                or name == 'default_adaptor'):
             return object.__getattribute__(self, name)
 
         return getattr(self.item_instance, name)
 
 
-def adaptor(*funcs, **adaptor_args):
+def adaptor(*funcs, **default_adaptor_args):
     """A pipe adaptor implementing the tree adaption logic
 
     It takes multiples unnamed arguments used as functions of the pipe, and
@@ -87,32 +84,29 @@ def adaptor(*funcs, **adaptor_args):
     Always returns a list of values
     """
 
-    pipe_adaptor_args = adaptor_args
     _funcs = []
     for func in funcs:
-        takes_args = 'adaptor_args' in get_func_args(func)
-        _funcs.append((func, takes_args))
+        accepts_args = 'adaptor_args' in get_func_args(func)
+        _funcs.append((func, accepts_args))
 
     def _adaptor(value, adaptor_args=None):
-        values = value if isinstance(value, (list, tuple)) else [value]
-        aargs = dict(t for d in [pipe_adaptor_args, adaptor_args or {}] for t in d.items())
+        values = arg_to_iter(value)
+        aargs = default_adaptor_args
+        if adaptor_args:
+            aargs = aargs.copy()
+            aargs.update(adaptor_args)
         pipe_kwargs = {'adaptor_args': aargs}
-
-        for func, takes_args in _funcs:
+        for func, accepts_args in _funcs:
             next = []
-            kwargs = pipe_kwargs if takes_args else {}
-
+            kwargs = pipe_kwargs if accepts_args else {}
             for val in values:
                 val = func(val, **kwargs)
-
-                if isinstance(val, (list, tuple)):
+                if hasattr(val, '__iter__'):
                     next.extend(val)
                 elif val is not None:
                     next.append(val)
-
             values = next
         return list(values)
 
     return _adaptor
 
-