Gemara

48b - Mishnah: If the water (for Nisuch ha'Mayim) became exposed we take new water from the Kiyor, for water or wine that was exposed is Pasul for the Mizbe'ach (perhaps a snake drank from it and put in venom).

50a - Question: Why is it Pasul? We can put it through a strainer, which will remove any venom that is inside!

Answer #1: Our Mishnah is unlike R. Nechemyah.

Beraisa: If dregs are on a strainer and the wine filters down (into a bottom Keli), we are concerned for Giluy;

R. Nechemyah says, this is only if the bottom Keli is exposed. We are not concerned if the top Keli is exposed, because snake's venom floats and stays on top.

Rejection: It is even like R. Nechemyah. R. Nechemyah permits only to a person, but he agrees that it is Pasul for Nesachim - "Hakrivehu Na l'Fechasecha..."

Bava Basra 97a - Rav: One must make Kidush on wine fitting for Nesachim.

Question: What does this come to exclude?

Answer: It excludes wine that cannot intoxicate, is diluted, was exposed, Temed, and wine that smells bad.

Beraisa: One should not bring any of these for Nesachim. If he did, it is Pasul.

Suggestion: Surely, he did not need to exclude Galuy. It is dangerous, and forbidden to drink!

Rejection: He comes to exclude Galuy, even if one passed it through a strainer according to R. Nechemyah;

It is still Pasul for Nesachim - "Hakrivehu Na l'Fechasecha..."

Rishonim

The Rif (Pesachim 22b) brings Rav's teaching.

Rambam (Hilchos Shabbos 29:14): Kidush must be on wine fitting for Nesachim. This excludes Galuy...

Poskim

Shulchan Aruch (YD 116:1): Chachamim forbade Galuy liquids, lest a snake drank from them and put in venom. Nowadays snakes are not common among us, so they are permitted.

Shulchan Aruch (OC 272:1): We do not make Kidush on exposed wine, even nowadays that we are not concerned for Giluy.

Question: In YD 116, the Tur forbids Galuy wine and says that straining it does not help. Here the Tur connotes that it is Pasul for Kidush, but one may drink it!

Answer (Bach DH v'Ika): The Halachah follows Chachamim of R. Nechemyah, who say that straining does not help. Even nowadays that we are not concerned for Giluy it is Pasul for Kidush, just like R. Nechemyah said that after straining it people may drink it but it is Pasul for Kidush.

Magen Avraham (1): Perhaps nowadays we are not concerned for if it was exposed a short time, especially since wine is not so abundant and governors are not so particular about this, as long as the taste or smell was not harmed.

Mishnah Berurah (3): This is only where wine is expensive, for there people are not so particular about a brief Giluy. One who makes Kidush on beer should be careful even about a brief Giluy. B'Di'eved, if there is nothing else to use for Kidush, Galuy wine or beer may be used.

Kaf ha'Chayim (7): If it was exposed the entire night, even b'Di'eved it should not be used.

Kaf ha'Chayim (8): The same applies to Havdalah. Even according to the opinion that Havdalah is mid'Rabanan, it was enacted like mid'Oraisa.

Kaf ha'Chayim (9): If an open bottle was in a closed cabinet, it is not a problem.

Kaf ha'Chayim (10): Some say that b'Di'eved, one who made Kidush on exposed wine was not Yotzei. It seems that one should not make Kidush again, since Kidush over wine is mid'Rabanan, especially nowadays when many are not particular about Giluy.

R. Akiva Eiger (DH Aval): The Ramban disqualifies white wine for Kidush ha'Yom, but allows it for Havdalah, for it is no worse than beer. According to this, it is also Kosher for morning Kidush. Perhaps the same applies to all Pesulim in this Siman.

Rebuttal (Bi'ur Halachah DH Al): The Ramban holds that white wine is not considered wine, but it is valid for Havdalah or morning Kidush because it is Chemar Medinah. Things which are Pasul because of Hakrivehu Na are Pasul for morning Kidush or Havdalah.