Just like you talk about “marus Ayin” on the other thread, when yeshivas collect money for their kollel and people who don’t go on vacations themselves or their kids don’t go on vacations and work hard but give tzedaka to kollels, see kollel yungerleit going on vacations it makes them wonder whether they should donate that money to the kollels or they should maybe use that money for vacation themselves or send their own kids who work very hard. Even if their own parents pay for their vacation, it still makes people think that maybe THEY should send their OWN children on vacation because THEY are just as deserving rather than send their hard earned money to support kollel.
Now before you start knocking me for what I just said, I am just pointing out why some people have a hard time with it, that’s all. Because it is the same marus ayin, no one wears a sign that says my parents paid for our vacation and it didn’t come out of kollel money. And no, people don’t assume that and why should they. If the parents can afford to support them, why should the kollel? This is usually the argument. Then others might say “how serious are they about their learning if they make time for vacations”? Personally I think it is very important for young couples to take time for themselves as a couple, but that is my own personal opinion, whether they go away on vacation or stay home and just do day trips or whatever because it is important for Shalom Bayis to bond as a couple.