The timing of Bartoli's retirement is indeed very strange, she seems to have given up on all the appearance fees and endorsements that would ensue and she had said that she was looking forward to New Haven etc and just enjoying playing tennis knowing that she could relax having achieved her goals. The timing is the only strange thing about it for me, very strange indeed. But then again Bartoli is a strange person, has an IQ of 175, higher than Einstein. It could be that she isn't that motivated by cashing in like every other player would be.
There is nothing strange whatsoever about her performances this year, however. It was her best season in terms of achievement, yes, but certainly not in terms of performance. She didn't perform at her highest level all season. She didn't even have to to win Wimbledon and it was no surprise to see her win any of those 7 matches.
In terms of testing, there was a big change in testing around or just before Wimbledon. I suspect it was certainly the first slam and perhaps the first or second/third tournament where they had blood-testing in competition and we saw Wozniacki tweet her surprise at being tested after a win at Eastbourne a couple of weeks beforehand. Previously it was exclusively loser-targeted testing before that with a tournament winner only being tested after the final.
Perhaps this caught a few players by surprise as we saw some shock exits from players, some without playing a match (withdrawals). I am not sure what the position is on withdrawing players being tested, however. Look at the Troicki case where he was willing to give urine but not blood and willing to undergo a ban as a result. I reckon he was caught totally by surprise by the requirement to give blood. His excuse was that he was feeling ill and giving blood would have made him worse, so he was willing to risk a two year ban so that he wouldn't feel worse?!! Expect this to be reduced on appeal.
But the shock early exits of some of the bigger players could be explained by the UK's ludicrous tax laws which tax a player 50% based on UK earnings and also tax a proportion of their worldwide endorsement/non-tennis income based on how long they have been in the UK during that year. For the very top players, these tax laws can actually result in them having to pay more tax than what they win in UK prize money, ie it can actually cost them money to play in the UK. This is why Federer and Nadal have prepared for the grass season/Wimbledon in Halle, Germany in recent years and not in Queens or in the UK. It is almost insulting to these players that they effectively have to pay money to play in the UK, costing more and more the longer they are in the UK.
For me the Cilic case is obviously much more suspicious than Bartoli, and as THASP has said, it constitutes a form of Omerta by the ITF in not making any details public when he is obviously banned from competition for some period. There was talk of Cilic having missed a few OOC tests years ago but as always this info was based on one or two quotes made by obscure people.