I'd like to keep it, and "dated" is probably better than "rare".

@@ -13 +13 @@
-<misc>&rare;</misc>
+<misc>&dated;</misc>

Google N-gram Corpus Counts
╭─ーーーー─┬────────╮
│ 生セラ　 │    269 │
│ ブルセラ │ 71,271 │ - cross-referenced entry
╰─ーーーー─┴────────╯

None of the works cited assume that the readers already know what the word means. References like these don't make a convincing case that a word is an established term that is worth recording in a dictionary.

Since the word is rare, slangy, and describes a short-lived phenomenon from 20 years ago that may have never been widespread, I wouldn't object to dropping the entry.

If it stays I think we need mention something about this being "in front of an audience," since that's the key aspect that distinguishes this from ブルセラ.

@@ -13 +13,3 @@
-<gloss>shop where schoolgirls remove and sell their underwear, etc.</gloss>
+<misc>&rare;</misc>
+<misc>&sl;</misc>
+<gloss>shop where schoolgirls remove and sell their underwear in front of an audience</gloss>

I originally saw this in Hideo Yamamoto's manga series Homunculus (~2004): https://i.imgur.com/fkF0Zph.png. You're probably not seeing many modern results because the practice was made illegal, but the references show that this was a thing.

生セラ	269

I doubt this is a common enough thing to warrant an entry. A Google search returns very few relevant results.

Charming.

@@ -13 +13 @@
-<gloss>shop where schoolgirls take off and sell their underwear, etc., to viewers</gloss>
+<gloss>shop where schoolgirls remove and sell their underwear, etc.</gloss>