diff --git a/Orange/widgets/visualize/owscatterplotgraph.py b/Orange/widgets/visualize/owscatterplotgraph.py
index 24e48d27ea5..e24d322a85c 100644
--- a/Orange/widgets/visualize/owscatterplotgraph.py
+++ b/Orange/widgets/visualize/owscatterplotgraph.py
@@ -128,7 +128,8 @@ def restoreAnchor(self, anchors):
         anchor, parentanchor = anchors
         self.anchor(*bound_anchor_pos(anchor, parentanchor))
 
-    def paint(self, painter, option, widget=None):
+    # pylint: disable=arguments-differ
+    def paint(self, painter, _option, _widget=None):
         painter.setPen(self.__pen)
         painter.setBrush(self.__brush)
         rect = self.contentsRect()
@@ -619,7 +620,7 @@ def _get_jittering_tooltip(self):
     def update_jittering(self):
         self.update_tooltip()
         x, y = self.get_coordinates()
-        if x is None or not len(x) or self.scatterplot_item is None:
+        if x is None or len(x) == 0 or self.scatterplot_item is None:
             return
         self._update_plot_coordinates(self.scatterplot_item, x, y)
         self._update_plot_coordinates(self.scatterplot_item_sel, x, y)
@@ -834,7 +835,7 @@ def update_coordinates(self):
         the complete update by calling `reset_graph` instead of this method.
         """
         x, y = self.get_coordinates()
-        if x is None or not len(x):
+        if x is None or len(x) == 0:
             return
         if self.scatterplot_item is None:
             if self.sample_indices is None:
@@ -1053,9 +1054,9 @@ def _get_continuous_colors(self, c_data, subset):
         # Reuse pens and brushes with the same colors because PyQtGraph then
         # builds smaller pixmap atlas, which makes the drawing faster
 
-        def reuse(cache, fn, *args):
+        def reuse(cache, fun, *args):
             if args not in cache:
-                cache[args] = fn(args)
+                cache[args] = fun(args)
             return cache[args]
 
         def create_pen(col):
@@ -1113,7 +1114,7 @@ def _get_discrete_colors(self, c_data, subset):
 
     def update_colors(self):
         """
-        Trigger an update of point sizes
+        Trigger an update of point colors
 
         The method calls `self.get_colors`, which in turn calls the widget's
         `get_color_data` to get the indices in the pallette. `get_colors`
diff --git a/Orange/widgets/visualize/tests/test_owscatterplotbase.py b/Orange/widgets/visualize/tests/test_owscatterplotbase.py
index 9dc7e26fba2..ce04126033e 100644
--- a/Orange/widgets/visualize/tests/test_owscatterplotbase.py
+++ b/Orange/widgets/visualize/tests/test_owscatterplotbase.py
@@ -58,6 +58,7 @@ def setUp(self):
     # pylint: disable=keyword-arg-before-vararg
     def setRange(self, rect=None, *_, **__):
         if isinstance(rect, QRectF):
+            # pylint: disable=attribute-defined-outside-init
             self.last_setRange = [[rect.left(), rect.right()],
                                   [rect.top(), rect.bottom()]]
 
@@ -308,12 +309,13 @@ def test_sampling_keeps_selection(self):
 
     base = "Orange.widgets.visualize.owscatterplotgraph.OWScatterPlotBase."
 
+    @staticmethod
     @patch(base + "update_sizes")
     @patch(base + "update_colors")
     @patch(base + "update_selection_colors")
     @patch(base + "update_shapes")
     @patch(base + "update_labels")
-    def test_reset_calls_all_updates_and_update_doesnt(self, *mocks):
+    def test_reset_calls_all_updates_and_update_doesnt(*mocks):
         master = MockWidget()
         graph = OWScatterPlotBase(master)
         for mock in mocks:
@@ -443,6 +445,7 @@ def impute_max(size_data):
 
         graph = self.graph
 
+        # pylint: disable=attribute-defined-outside-init
         self.master.get_size_data = lambda: d
         self.master.impute_sizes = impute_max
         d = np.arange(10, dtype=float)
@@ -1162,6 +1165,7 @@ def test_shapes_nan(self):
         def impute0(data, _):
             data[np.isnan(data)] = 0
 
+        # pylint: disable=attribute-defined-outside-init
         self.master.impute_shapes = impute0
         d = np.arange(10, dtype=float) % 3
         d[2] = np.nan