For me it depends on the series and context. If it is clearly just fanservice, then I have no problem with it. I’ve gone through several series with 1-2 百合 characters, but it’s never expected to go anywhere, so I don’t get my hopes up and just enjoy the character interactions that come from it.
For example, in ゆるゆり | L20 nearly every character is into another character (all girls), but the entire series relies on nothing ever happening between them.
In ご注文はうさぎですか? 1 | L24, one of the main characters has a crush on another, but from context it’s clear that they will never get together.
I don’t have any problem with either of these series because it’s made clear that nothing will ever happen, so I don’t get my hopes up.
On the other hand, in まちカドまぞく | L35 , the two main characters clearly developed strong feelings for each other over the series. One even confessed before immediately back-pedaling.
When they inevitably don’t end up together by the end I will be very upset. In this case, if I was reading it after it was finished, I would definitely want to know ahead of time if they ended up together or not because focus is put on their relationship and feelings through-out the series.
I would consider it a spoiler in this case though. So I probably wouldn’t see it because I wouldn’t want to see the rest of the spoiler tags, which was the original issue that started this conversation anyway.
The best solution, if a little inconvenient, might be to search for the series with the search bar.
Then modify the search to include the spoiler tag in question.
That way you can see if that specific tag is present without seeing the other spoiler tags.