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http://cgi.ebay.de/ws/eBayISAPI.dll?...m=160348801838
question is not for the authorship or falsification, and for spelling.
Have any grammatical or spelling mistakes in art posters, banners, signs, etc.?
Work bezgrammotnyh foreign masters, as an example, do not count.

I personally came across paintings, and original, with examinations, where the pre-revolutionary artists did not write the letter "v" in the words where it should be.
And here is a recent example from the forum, a grammatical error in the title picture:
http://forum.artinvestment.ru/showthread.php?t=33865