Piotr wrote:
 Apparently some amount of affrication produces a more satisfactory imitation of a Russian accent than targeting on somethging like the stage pronunciation of palatalised dentals. I wonder if it also sounds more successful from a native speaker's point of view.
 Yes, that's what I was writing about. Standard Lithuanian palatalizes consonants before a front vowels (and this is not the case for some dialects), but standard Russian affricatizes them to some extent as well. And of course it sounds more successful (if only this amount of affrication doesn't turn the consonants into proper affricates like those of Polish).
An afterthought about what Sergei wrote about vowels: if a Pole attempts to imitate Polish spoken with a Russian accent, the most obvious thing to do (apart from modifying the palatals) is vowel drawling with all the diphthongoid or triphthongoid effects caused by CV and VC transitions.
Hmm, sounds strange, as in standard Russian unstressed vowels are shortened. May be this average Pole met dialects' speakers rather than standard Russian speakers?