"is unreliable for" is a correct and usable phrase in written English.
It is used when you are referring to someone or something being unreliable in a particular way or for a particular purpose. For example, "The public bus system in our city is unreliable for getting to appointments on time."
Feeling a child's forehead is unreliable for determining the presence of a fever.
Carbon dating is unreliable for objects older than about 30,000 years, but uranium-thorium dating may be possible for objects up to half a million years old, Dr. Zindler said.
Experts in anesthetics have warned that midazolam is a drug that is unreliable for inducing a coma, while the use of a paralytic could disguise that an inmate was suffering cruel and unusual punishment.
Foos is unreliable: for example, he claimed that he began spying on motel guests in 1966; Talese discovered that he didn't purchase the motel until 1969, but never apparently investigated that inconsistency, either.
On the whole, 2-D CFD is unreliable for predicting stall (maximum lift and the angle of attack at which it occurs); in most cases, maximum lift is overpredicted, but for some configurations the opposite occurs.
The three field studies reported suggest that the ADF adaptation of HFACS is unreliable for incident analysis at the ATC unit level, and may therefore be invalid in this context.
Polygraphs are unreliable for a number of reasons, he says.
In fact, Medicare was started in 1965 because private insurance was unreliable for them.
The results also suggested that the user-seal-check may be unreliable for detecting gross leakage.
Note: Spectral fit parameters may be unreliable for sources at large off-axis angles, where background levels can be high.
