Well-known kinetic hydrate inhibitors (KHIs) such as poly(N-vinylcaprolactam) (PVCap), poly(N-vinylpyrrolidone) (PVP), and 1:1 N-vinylcaprolactam:N-vinylpyrrolidone (VCap:VP) copolymer have been subjected to a range of treatments to determine their reliability and whether the treatment conditions could affect the KHI performance, both positively or negatively. This included thermal aging (at varying temperatures, at varying pH, and in monoethylene glycol (MEG) solvent), treatment with microwaves or ultrasound, ball-milling, and oxidizing agents (household bleach or hydrogen peroxide, also with heat). In addition, samples of commercial polymer solutions kept for up to 15 years were also tested for KHI performance to determine their long-term reliability. Testing was carried out using a synthetic natural gas mixture in steel rocking cells using slow constant cooling starting at ca. 76 bar. All samples of PVCap and 1:1 VP:VCap showed good KHI performance to the first sign of hydrate formation, but older samples showed a better ability to inhibit crystal growth. KHI polymer testing after treatment with microwaves or ultrasound, or thermal aging (at varying temperatures, varying field pH, and in MEG solvent up to 160 degrees C) showed little loss of performance. Oxidizing agents, particularly sodium hypochlorite solution, worsened the KHI performance.