As the title suggests how do I know when they are just making an excuse?

I have seen some people (Women I ask out) use it as an excuse when it comes to going on a date but I don't know sometimes because of how many variants/waves there have been. For example, there was one woman who asked for my snapchat and then when I asked her out she said she didn't know because covid was surging again... and then I saw her at a concert. So obviously she wasn't really interested. Recently I invited a woman at work (a very large grocery store. Like a Walmart plus sized store) to a party a few days after I got her number but she said she couldn't risk getting covid because she had surgery the following week. I think this was valid but she didn't wear a mask at work until a few days ago when they made us so I'm not entirely sure how important the surgery really is to her.

I'm well aware people will make literally any and every excuse before they tell you they aren't interested. Hell, I had one woman tell me her grandpa fell down the stairs and was in the ER before our date and a few days later I asked her brother about it and he was like "Wtf are you talking about dude?". But yeah I was wondering if there was any way or perhaps a better way I could tell?

Thank you