I'm sure of it when in mil power (Max Continous Thrust without Afterburner / AB) or below. Honestly, you only know they are in AB during the daytime when they are close (you can either see it or can tell by how he is maneuvering). At that point you aren't looking at exhaust plume so much as to where he is pointing or who he is turning on (attacking). My guess it was in AB as well, maybe just not as bad.
There was a big push here in the states to get rid of the exhaust plume and the engine manufacturers have stepped up with it basically not being a problem on equipment fielded since Vietnam. I don't think the French or Brit stuff smokes either (have fought Tornados, Mirage F-1s and 2000s).
Historically the Russian made engines have no where near the lifespan of US stuff. The MiG-29s the Germans flew had slightly detuned engines, which were pulled at 300 hours and mildly overhauled. 300 hours later they were tossed. I got this word of mouth from them so have no written sources. The F-15 versions I flew had either F100-100 or -220 (FADEC version) engines, and those have stayed in the plane for up to 2000 hours. Again, this was word of mouth from a crew chief in my ANG unit. The Indians bought late model Flankers (Su-27 type) and have butted heads with the Russians over engines (life span, service, and replacements). Buying Russian equipment is cheaper, much, than Western stuff. The downside is you have to deal with the Russians who are a pain in the are (PITA), parts can be very expensive, and or difficult to get (not much manufacturer support).