After Bottling My Beer tastes sweet (yuck)

I've done probably 100-150 bottles with sugar drops, no duds. It's hard to see how it could fail unless you're cold crashing/lagering for 3-4 months and dropping all the available yeast out. In any case, I'll take the occasional dud over this horrible sickly-sweet thing that still haunts my nightmares and which almost knocked me out of homebrewing entirely.

I fermented a batch of beer using S-04 at around 60 degrees and got really strong what I would call peach flavors. I didn't find the flavor pleasant. At 65+ S-04 has been very good to me. The esters it throws at the higher temps are very nice. I even had one get away from me from me since I use a cooler with ice packs. It fermented at 80 degrees and there was fusals. I had saved one bottle of it for 4 months and the hot fusals had calmed down and the big esters were delicious. I wouldn't ferment that high on purpose because every bottle of that beer gave me a minor fusal headache, but I wouldn't ferment S-04 at 62 or below either. To use S-04 regularly, I would want to have a electronically controlled fermentation chamber.

BTW what's with everyone saying that "homebrew" flavor as if it's a bad thing?

Ok, so almost 1 year and several batches later I have come to a conclusion to explain some of the contributing factors of this slightly sweet bi-product with my extract brewing setup. After thoroughly scrubbing all my bottles to get rid of any OXY residue and only using PBW it NEVER came back again except for ONE BATCH. This one batch mirrored some of the conditions that most likely contributed to the 2 in a row that had me scratching my head a year ago.

1) Both off beers were done using 1 packet of liquid yeast without a starter
2) Both off beers had a starting gravity around 1.070

After using both liquid as well as dry yeast (S-04 & S-05) and keeping the starting gravities around 1.058-1.060 or lower, I never had any issues again. For those 2 slightly sweet beer batches, even though my final gravity was in the correct range for the beer to be finished, the feedback I got from several brewery owners who gave me feedback told me two things

1) the beer didn't taste bad (like an infection, or any of the other off flavor suspects).
2) the beer just tastes like it's possibly under attenuated or slightly unfinished

For these reasons, the bottles needing to be cleaned more thoroughly with PBW and NOT OXY ( with the OXY possibly leaving a residue) might have been a small contributing factor. The sweet taste was most likely a result of a higher starting gravity in combination with use of a liquid yeast which resulted in an overall lower yeast cell count for what was needed for the beer to fully attenuate. In my naivete, I also didn't realize the speed at which liquid yeast loses about 20% of its viable yeast cells every month.
I still won't be using OXY anymore just as a precaution. Hope this helps anyone.