diff --git a/dvc/remote/base.py b/dvc/remote/base.py
index 8738c2d07..34a60e915 100644
--- a/dvc/remote/base.py
+++ b/dvc/remote/base.py
@@ -108,7 +108,47 @@ class RemoteBase(object):
         raise NotImplementedError
 
     def changed(self, path_info, checksum_info):
-        raise NotImplementedError
+        """Checks if data has changed.
+
+        A file is considered changed if:
+            - It doesn't exist on the working directory (was unlinked)
+            - Checksum is not computed (saving a new file)
+            - The checkusm stored in the State is different from the given one
+            - There's no file in the cache
+
+        Args:
+            path_info: dict with path information.
+            checksum: expected checksum for this data.
+
+        Returns:
+            bool: True if data has changed, False otherwise.
+        """
+
+        logger.debug("checking if '{}'('{}') has changed."
+                     .format(path_info, checksum_info))
+
+        if not self.exists(path_info):
+            logger.debug("'{}' doesn't exist.".format(path_info))
+            return True
+
+        checksum = checksum_info.get(self.PARAM_CHECKSUM)
+        if checksum is None:
+            logger.debug("checksum for '{}' is missing.".format(path_info))
+            return True
+
+        if self.changed_cache(checksum):
+            logger.debug("cache for '{}'('{}') has changed."
+                         .format(path_info, checksum))
+            return True
+
+        actual = self.save_info(path_info)[self.PARAM_CHECKSUM]
+        if checksum != actual:
+            logger.debug("checksum '{}'(actual '{}') for '{}' has changed."
+                         .format(checksum, actual, path_info))
+            return True
+
+        logger.debug("'{}' hasn't changed.".format(path_info))
+        return False
 
     def save(self, path_info):
         raise NotImplementedError
diff --git a/dvc/remote/gs.py b/dvc/remote/gs.py
index 8530f36b2..4288bf39a 100644
--- a/dvc/remote/gs.py
+++ b/dvc/remote/gs.py
@@ -63,19 +63,6 @@ class RemoteGS(RemoteBase):
         return {self.PARAM_CHECKSUM: self.get_md5(path_info['bucket'],
                                                   path_info['path'])}
 
-    def changed(self, path_info, checksum_info):
-        if not self.exists(path_info):
-            return True
-
-        md5 = checksum_info.get(self.PARAM_CHECKSUM, None)
-        if md5 is None:
-            return True
-
-        if self.changed_cache(md5):
-            return True
-
-        return checksum_info != self.save_info(path_info)
-
     def copy(self, from_info, to_info, gs=None):
         gs = gs if gs else self.gs
 
diff --git a/dvc/remote/hdfs.py b/dvc/remote/hdfs.py
index ec1fdf105..fb8c75bd4 100644
--- a/dvc/remote/hdfs.py
+++ b/dvc/remote/hdfs.py
@@ -84,19 +84,6 @@ class RemoteHDFS(RemoteBase):
 
         return {self.PARAM_CHECKSUM: self.checksum(path_info)}
 
-    def changed(self, path_info, checksum_info):
-        if not self.exists(path_info):
-            return True
-
-        checksum = checksum_info.get(self.PARAM_CHECKSUM, None)
-        if checksum is None:
-            return True
-
-        if self.changed_cache(checksum):
-            return True
-
-        return checksum_info != self.save_info(path_info)
-
     def save(self, path_info):
         if path_info['scheme'] != 'hdfs':
             raise NotImplementedError
diff --git a/dvc/remote/local.py b/dvc/remote/local.py
index 86acc79a0..99e6884a4 100644
--- a/dvc/remote/local.py
+++ b/dvc/remote/local.py
@@ -429,26 +429,6 @@ class RemoteLOCAL(RemoteBase):
 
         return {self.PARAM_CHECKSUM: self.state.update(path_info['path'])}
 
-    def changed(self, path_info, checksum_info):
-        """
-        A file is considered changed if:
-            - It doesn't exist on the working directory (was unlinked)
-            - Checksum is not computed (saving a new file)
-            - The checkusm stored in the State is different from the given one
-            - There's no file in the cache
-        """
-        if not self.exists(path_info):
-            return True
-
-        md5 = checksum_info.get(self.PARAM_CHECKSUM, None)
-        if md5 is None:
-            return True
-
-        if self.changed_cache(md5):
-            return True
-
-        return checksum_info != self.save_info(path_info)
-
     def remove(self, path_info):
         if path_info['scheme'] != 'local':
             raise NotImplementedError
diff --git a/dvc/remote/s3.py b/dvc/remote/s3.py
index 420985520..75dc3f6aa 100644
--- a/dvc/remote/s3.py
+++ b/dvc/remote/s3.py
@@ -98,19 +98,6 @@ class RemoteS3(RemoteBase):
         return {self.PARAM_CHECKSUM: self.get_etag(path_info['bucket'],
                                                    path_info['path'])}
 
-    def changed(self, path_info, checksum_info):
-        if not self.exists(path_info):
-            return True
-
-        etag = checksum_info.get(self.PARAM_CHECKSUM, None)
-        if etag is None:
-            return True
-
-        if self.changed_cache(etag):
-            return True
-
-        return checksum_info != self.save_info(path_info)
-
     def copy(self, from_info, to_info, s3=None):
         s3 = s3 if s3 else self.s3
 
diff --git a/dvc/remote/ssh.py b/dvc/remote/ssh.py
index 2758ef903..54030105d 100644
--- a/dvc/remote/ssh.py
+++ b/dvc/remote/ssh.py
@@ -218,19 +218,6 @@ class RemoteSSH(RemoteBase):
 
         return {self.PARAM_CHECKSUM: self.md5(path_info)}
 
-    def changed(self, path_info, checksum_info):
-        if not self.exists(path_info):
-            return True
-
-        md5 = checksum_info.get(self.PARAM_CHECKSUM, None)
-        if md5 is None:
-            return True
-
-        if self.changed_cache(md5):
-            return True
-
-        return checksum_info != self.save_info(path_info)
-
     def save(self, path_info):
         if path_info['scheme'] != 'ssh':
             raise NotImplementedError