Hmmm, lots of conflicting theories.
Regardless of the tattoo being a myth, thats a different discussion.
Well, I think whether it is a myth is very important in this discussion. If it is a myth, that means there is no absolutely correct version of the tattoo since the tattoo did not exist in the 1st place. If that's the case, the discussion becomes how later generations come up with the various versions, instead of figuring out what the original was.
Why would the spelling change from time to time? Is it because like RedSword mentioned that people do not want to "quote" others out of respect?
And do all spelling have basically the same meaning?
Most of the mentioning of the tattoo came from fictional novels in the Yuan, Ming and Qing dynasties when this type of novels were very popular. Almost all the famous ancient Chinese novels were written in this time, the 3 kingdom, Journey to the West, Shui Hu, Sui Tang, etc. So it all depended on how the authors understood the phrase. Some author might think "尽" could represent Yue Fei's loyalty better while others might think "精" would be better. It's all about personal taste and interpretation. It's like the famous story of a poet spending a lot of time contemplating whether to use "to push" or to use "to knock" in one of his poem. He finally decided on one word while someone else in a similar situation might pick the other word.
I don't think it's because people not wanting to quote others. There have been many many writings about Yue Fei, only 2-3 versions of the tattoo exist. This means many authors have been quoting others. Additionally, Those carvings shown in the original post of this thread were all phrases that had been quoted by many for centuries and were NOT invented by the writers of the carving. So in other words, they were all quoting others. Again, it's only the matter of personal taste that dictated which version they picked.
Also most sources seem to be wikipedia type of sources. None of them are "official" or "academic".
Yes, most sources are Wiki type. But many of those have citations of the original articles and list names of the books, authors, time, places, etc, such as this:
曾孙岳珂所著的《金陀革编》也没有记录,
元人所编的《宋史本传》，书云：“初命何铸鞠之，飞裂裳，以背示铸，有‘尽忠报国’四大字，深入肤理”,
明代成化年间创作的《精忠记》，也仅提及岳飞背脊有“赤心救国”字样,
嘉靖三十一年（1552年）熊大本的《武穆精忠传》记有岳飞请工匠在背上深刺“精忠报国”四字,
明末，由李梅草创，冯梦龙改定的《精忠旗传奇》，内称：“史言飞背有‘精忠报国’四大字，系飞令张宪所刺”,
“岳母刺字”则最早见于清乾隆年间，杭州钱彩评《精忠说岳》，该书第22回，回目“结义盟王佐假名，刺精忠岳母训子”.
Citing original work, giving names of the authors, title of the work, time when it was written, as well as what was written in these books, this is as academic as you can get. The discussion in 百度百科 is very academic, in a sense that it had a hypothesis at the beginning and presented evidence to support the hypothesis. No hear-say, no guesses, no imagining of any sort... Only solid evidence with names, time, titles.
However, in no way I am saying that the hypothesis in 百度百科 is correct. Simply, their point is the most convincing with the most solid evidence. If you disagree with this particular hypothesis, that is perfect fine. The only thing is you have to present your evidence to support your hypothesis. In fact, I would expect many such evidence exist. Otherwise, we would not be talking about this supposed tattoo. Discrediting the evidence presented in 百度百科 is NOT the way to do it.
Also, compared to those discussions based on hear-say and guesses, any source is better than none.
Also, 有学者认为，此时的“精忠报国”四字是受宋高宗御赐“精忠岳飞”4字的误导
This might be why people use "精"...
