I'm just not convinced by those big box stores and to be honest I want to support independents as ultimately Pets at Home will be cheaper as they have buying power. Now if everyone votes with their pocket and shops at those big box places the smaller stores will struggle and slowly disappear, then we're all left with only shopping in those big places, which is something I'd hate to see. And personally I love going to the independent little places, speaking with the owners, benefiting from real advice and seeing varied stock rather than the same generic fish and speaking with someone of college age on minimum wage. I know day to day in life voting with your feet in terms of a supermarket vs your local butcher, greengrocer, etc, isn't that easy due to work, etc, but where I can I will and aquatics wise I always do my best to. Same with buying online. I ordered a filter earlier from a sponsor on here who doesn't have it in stock and so it will take a week or two to get to me. The same filter is on Amazon with free next day delivery for the same price. Fortunately I don't need it straight away so that obviously helps
In terms of Pets at Home stock, here's my direct experience. I went in one a while ago just for a look as we were at a retail park and like you was tempted by their prices and to be fair some of the fish looked decent. Now in the bank of 9 display tanks there was one tank which was covered with a sign basically saying the fish were ill, being treated and not for a sale (from that one tank, not the bank). Whilst stood there the assistant came over and asked if they could help and I asked about the tank with the ill fish (which after pulling the sign back showed that they had fungus) and so I asked him to confirm if the tank with the ill fish was on the same bank, loop, filter as the rest. He wasn't sure and brought over the assistant manager who after sliding some covers back and forth confirmed it was. Now I wasn't sure if I was going to buy anything anyway but needless to say I didn't