diff --git a/js/src/tests/js1_8_1/trace/jstests.list b/js/src/tests/js1_8_1/trace/jstests.list
index ece7830577bd..e56c8ee66375 100644
--- a/js/src/tests/js1_8_1/trace/jstests.list
+++ b/js/src/tests/js1_8_1/trace/jstests.list
@@ -2,7 +2,7 @@ url-prefix ../../jsreftest.html?test=js1_8_1/trace/
 script math-trace-tests.js
 script regress-451673.js # slow
 script regress-451974-01.js
-random script regress-451974-02.js # bug 524734
+random script regress-451974-02.js # this is a bogus timing test (see bug 524734)
 random script regress-452498-01.js
 script regress-458838.js
 script regress-462459-01.js
diff --git a/layout/reftests/bidi/reftest.list b/layout/reftests/bidi/reftest.list
index d57244f92ee7..1b44ab50be5e 100644
--- a/layout/reftests/bidi/reftest.list
+++ b/layout/reftests/bidi/reftest.list
@@ -4,7 +4,7 @@
 == bidi-001-v.html bidi-001-ref.html
 == bidi-002.html bidi-002-ref.html
 == bidi-003.html bidi-003-ref.html
-fails-if(MOZ_WIDGET_TOOLKIT!="windows") == bidi-004.html bidi-004-ref.html # Bug 386567 (Linux), bug 386573 (Mac)
+fails-if(MOZ_WIDGET_TOOLKIT!="windows") == bidi-004.html bidi-004-ref.html # Bug 386567 (Linux), bug 401078 (Mac)
 fails-if(MOZ_WIDGET_TOOLKIT!="windows") == bidi-004-j.html bidi-004-ref.html
 == bidi-005.html bidi-005-ref.html
 == bidi-006.html bidi-006-ref.html
diff --git a/layout/reftests/bugs/reftest.list b/layout/reftests/bugs/reftest.list
index 2deafa3b5681..ad5e55acec26 100644
--- a/layout/reftests/bugs/reftest.list
+++ b/layout/reftests/bugs/reftest.list
@@ -552,7 +552,7 @@ fails-if(MOZ_WIDGET_TOOLKIT=="cocoa") == 356774-1.html 356774-1-ref.html # proba
 == 367612-1f.html 367612-1-ref.html
 != 367612-1g.html 367612-1-ref.html
 == 368020-1.html 368020-1-ref.html
-random == 368020-2.html 368020-2-ref.html # bug 368157 (gtk), bug 403181
+random == 368020-2.html 368020-2-ref.html # bug 403181 comment 52 explains why this test is disabled.
 fails == 368020-3.html 368020-3-ref.html # bug 368085
 fails == 368020-4.html 368020-4-ref.html # bug 368085
 random-if(MOZ_WIDGET_TOOLKIT=="gtk2") == 368020-5.html 368020-5-ref.html # bug 388591
@@ -835,7 +835,7 @@ HTTP(..) == 404149-1.xul 404149-1-ref.xul # HTTP for fonts directory access
 == 404301-1.html 404301-1-ref.html
 == 404309-1a.html 404309-1-ref.html
 == 404309-1b.html 404309-1-ref.html
-!= data:application/xml,<foo/> data:text/plain, # bug 404419
+!= data:application/xml,<foo/> data:text/plain, # ensure we pretty-print this XML instead of letting it appear blank (test for bug 404419)
 == 404553-1.html 404553-1-ref.html  # assertion test, also tests that marquee binding is applied correctly
 == 404666-1.html 404666-1-ref.html
 == 404666-2.html 404666-2-ref.html
diff --git a/layout/reftests/font-face/reftest.list b/layout/reftests/font-face/reftest.list
index c3fb814cecdf..02a061de2c0d 100644
--- a/layout/reftests/font-face/reftest.list
+++ b/layout/reftests/font-face/reftest.list
@@ -114,10 +114,9 @@ HTTP(..) != 507960-1-bad-woff-sig.html 507960-1-ref.html
 HTTP(..) != 507960-1-bad-offset-woff.html 507960-1-ref.html
 HTTP(..) != 507960-1-woff-bad-hint.html 507960-1-ref.html
 
-# Bug 523717
+# Tests for bug 523717
 HTTP(..) == underline-offset-change-1.html underline-offset-change-1-ref.html
 HTTP(..) == underline-offset-change-2.html underline-offset-change-2-ref.html
 fails-if(MOZ_WIDGET_TOOLKIT=="cocoa") fails-if(MOZ_WIDGET_TOOLKIT=="windows") HTTP(..) != underline-offset-change-1-ref.html underline-offset-change-2-ref.html # Bug 534132
 
-# Bug 534352
 HTTP(..) != 534352-1-extra-cmap-sentinel.html 534352-1-extra-cmap-sentinel-ref.html
diff --git a/layout/reftests/forms/reftest.list b/layout/reftests/forms/reftest.list
index 6af364476ec5..a99a78d1287c 100644
--- a/layout/reftests/forms/reftest.list
+++ b/layout/reftests/forms/reftest.list
@@ -1,8 +1,8 @@
 
 == checkbox-label-dynamic.html checkbox-label-dynamic-ref.html
-== checkbox-radio-stretched.html checkbox-radio-stretched-ref.html # bug 464589
+== checkbox-radio-stretched.html checkbox-radio-stretched-ref.html # test for bug 464589
 
-== input-file-width-clip-1.html input-file-width-clip-ref.html # bug 409587
+== input-file-width-clip-1.html input-file-width-clip-ref.html # test for bug 409587
 == input-hidden-border.html about:blank
 == input-text-size-1.html input-text-size-1-ref.html
 == input-text-size-2.html input-text-size-2-ref.html
@@ -10,10 +10,10 @@ HTTP(..) == input-text-baseline-1.html input-text-baseline-1-ref.html
 HTTP(..) == input-text-centering-1.xul input-text-centering-1-ref.xul
 HTTP(..) == text-control-baseline-1.html text-control-baseline-1-ref.html
 == input-text-dynamic-height-1.xul input-text-dynamic-height-1-ref.xul
-== textbox-align-baseline-1.xul textbox-align-baseline-1-ref.xul # bug 494901
+== textbox-align-baseline-1.xul textbox-align-baseline-1-ref.xul # test for bug 494901
 
 == radio-label-dynamic.html radio-label-dynamic-ref.html
-== out-of-bounds-selectedindex.html out-of-bounds-selectedindex-ref.html # bug 471741
+== out-of-bounds-selectedindex.html out-of-bounds-selectedindex-ref.html # test for bug 471741
 != indeterminate-checked.html indeterminate-checked-notref.html
 != indeterminate-unchecked.html indeterminate-unchecked-notref.html
 != indeterminate-native-checked.html indeterminate-native-checked-notref.html
diff --git a/modules/libpr0n/test/reftest/color-management/reftest.list b/modules/libpr0n/test/reftest/color-management/reftest.list
index 41e826d57463..ee6e16adbcf8 100644
--- a/modules/libpr0n/test/reftest/color-management/reftest.list
+++ b/modules/libpr0n/test/reftest/color-management/reftest.list
@@ -1,7 +1,7 @@
 # Colormangement
 
-# bug 489133 and bug 460520
+# test for bug 489133, test for bug 460520
 == invalid-chrm.png invalid-chrm-ref.png
 == invalid-whitepoint.png invalid-chrm-ref.png
-# bug 488955
+# test for bug 488955
 == trc-type.html trc-type-ref.html
diff --git a/modules/libpr0n/test/reftest/reftest.list b/modules/libpr0n/test/reftest/reftest.list
index 5d56c2ce731d..ec24acf8c1c5 100644
--- a/modules/libpr0n/test/reftest/reftest.list
+++ b/modules/libpr0n/test/reftest/reftest.list
@@ -1,4 +1,4 @@
-# Check for 24-bit color mode (bug 414720)
+# Check for 24-bit color mode (test for bug 414720)
 == colordepth.html about:blank
 
 # "PngSuite, the official set of PNG test images"