You can see the numbers using the following query on Data Explorer:
https://data.stackexchange.com/stackoverflow/query/60587/suggested-edit-stats-for-anon
For all time:
Approved Rejected Good Site Name
-------- -------- ------- ---------
2635 4568 36.58% StackOverflow
351 330 51.54% SuperUser
167 149 52.85% ServerFault
7 12 36.84% Cooking
12 5 70.59% Game Developers
173 213 44.82% Gaming
11 5 68.75% GIS
126 50 71.59% Mathematics
13 6 68.42% Photography
24 15 61.54% Statistical Analysis
28 16 63.64% Web Apps
19 19 50.00% Webmasters
125 48 72.25% Apple
76 5 93.83% Theoretical Computer Science
52 74 41.27% English Language and Usage
31 9 77.50% TeX - LaTeX
244 97 71.55% Ubuntu
17 3 85.00% User Interface
28 22 56.00% Unix and Linux
32 22 59.26% WordPress
77 53 59.23% Programmers
12 52 18.75% Android Enthusiasts
19 8 70.37% OnStartups
25 23 52.08% Physics
15 9 62.50% IT Security
19 5 79.17% Electronics and Robotics
17 8 68.00% Science Fiction
11 8 57.89% Code Review
8 8 50.00% Code Golf
28 10 73.68% Skeptics
40 14 74.07% Drupal Answers
8 8 50.00% Parenting
24 8 75.00% SharePoint
9 5 64.29% Jewish Life and Learning
39 2 95.12% Japanese Language and Usage
(edited to remove any sites with ~15 or less anonymous suggested edits, because sample is way too small to even look at)
So yeah, we get a high proportion of crappy edits, however also get a significant amount of good edits.
Anonymous sucks as an editor, she does not edit as much as we initially thought and has a high miss rate.
However, dealing with rejected edits is trivial, we ban anon really early so she can not wreak too much havoc, and she does help out quite frequently.
Overall, I see no reason to make any changes here.
SELECT COUNT (*) FROM SuggestedEdits WHERE RejectionDate IS NULL AND OwnerUserId IS NULL;
/SELECT COUNT (*) FROM SuggestedEdits WHERE RejectionDate IS NOT NULL AND OwnerUserId IS NULL;
)