I would say the majority of games labeled as trackball are not trackball games....
You're talking about mame32, right? You're right Mame32 lists other analog input games (except pedal and lightgun games) as "trackball" games. Also, I think mame32 uses the -listinfo data, which does include the errors described by Howard.
But I think the biggest mame32 problem is that most "trackball" games are spinner games.
Let me check... wow, I find, in the input list I linked prior:
97 games, including clones, are listed as having trackballs,
266 games have spinners (dotron + 2 clones have both trackball and spinner inputs listed in drivers),
150 games have AD stick inputs (2 games, aztrac & gtmr2 have spinner input),
55 games have paddle inputs (9 games also have AD stick),
for a total of 554 games (97 + 266 - 3 + 150 - 2 + 55 - 9).
Mame32 lists 552 games as trackball games; the extra two in my list are probably games with an analog input, but not shown as such with -listinfo; I can't tell which two though.
97 out of 552 is ~ 3 games really have trackball inputs out of every 17 listed in mame32.

I did not know it was
that bad.
-listinfo isn't that bad: 114 games listed as trackball games. Hmm, I need to check the 97 vs 114 numbers; back in a little.