This can be inferred from high accuracy of stateof-the-art POS tagging not only for English, but also most other languages such as Arabic, which reaches 97% for Arabic and English being at 97.32% (Gadde et al., 2011).
the performance of standard POS taggers for English is severely degraded on Tweets due to their noisiness and sparseness (Ritter et al., 2011).